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app-MAIL-temp/email_handler.py
Adrià Casajús 44e0dd8635
Break using an alias as a mailbox loop in the email_handler.py (#1624) 
* Do not allow to use email alias as account email when linking

* Add missing status

* Remove TODO

* Also break contact as email loop

* Better test names

* Allow a reverse alias to send an email to an alias

* Ident fix

* Removed invalid test

---------

Co-authored-by: Adrià Casajús <adria.casajus@proton.ch>
2023-03-13 13:01:00 +01:00

2431 lines
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Python
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"""
Handle the email *forward* and *reply*. phase. There are 3 actors:
- contact: who sends emails to alias@sl.co address
- SL email handler (this script)
- user personal email: to be protected. Should never leak to contact.
This script makes sure that in the forward phase, the email that is forwarded to user personal email has the following
envelope and header fields:
Envelope:
mail from: @contact
rcpt to: @personal_email
Header:
From: @contact
To: alias@sl.co # so user knows this email is sent to alias
Reply-to: special@sl.co # magic HERE
And in the reply phase:
Envelope:
mail from: @contact
rcpt to: @contact
Header:
From: alias@sl.co # so for contact the email comes from alias. magic HERE
To: @contact
The special@sl.co allows to hide user personal email when user clicks "Reply" to the forwarded email.
It should contain the following info:
- alias
- @contact
"""
import argparse
import email
import time
import uuid
from email import encoders
from email.encoders import encode_noop
from email.message import Message
from email.mime.application import MIMEApplication
from email.mime.multipart import MIMEMultipart
from email.utils import make_msgid, formatdate, getaddresses
from io import BytesIO
from smtplib import SMTPRecipientsRefused, SMTPServerDisconnected
from typing import List, Tuple, Optional
import newrelic.agent
from aiosmtpd.controller import Controller
from aiosmtpd.smtp import Envelope
from email_validator import validate_email, EmailNotValidError
from flanker.addresslib import address
from flanker.addresslib.address import EmailAddress
from sqlalchemy.exc import IntegrityError
from app import pgp_utils, s3, config
from app.alias_utils import try_auto_create
from app.config import (
EMAIL_DOMAIN,
URL,
UNSUBSCRIBER,
LOAD_PGP_EMAIL_HANDLER,
ENFORCE_SPF,
ALERT_REVERSE_ALIAS_UNKNOWN_MAILBOX,
ALERT_BOUNCE_EMAIL,
ALERT_SPAM_EMAIL,
SPAMASSASSIN_HOST,
MAX_SPAM_SCORE,
MAX_REPLY_PHASE_SPAM_SCORE,
ALERT_SEND_EMAIL_CYCLE,
ALERT_MAILBOX_IS_ALIAS,
PGP_SENDER_PRIVATE_KEY,
ALERT_BOUNCE_EMAIL_REPLY_PHASE,
NOREPLY,
BOUNCE_PREFIX,
BOUNCE_SUFFIX,
TRANSACTIONAL_BOUNCE_PREFIX,
TRANSACTIONAL_BOUNCE_SUFFIX,
ENABLE_SPAM_ASSASSIN,
BOUNCE_PREFIX_FOR_REPLY_PHASE,
POSTMASTER,
OLD_UNSUBSCRIBER,
ALERT_FROM_ADDRESS_IS_REVERSE_ALIAS,
ALERT_TO_NOREPLY,
)
from app.db import Session
from app.email import status, headers
from app.email.rate_limit import rate_limited
from app.email.spam import get_spam_score
from app.email_utils import (
send_email,
add_dkim_signature,
add_or_replace_header,
delete_header,
render,
get_orig_message_from_bounce,
delete_all_headers_except,
get_spam_info,
get_orig_message_from_spamassassin_report,
send_email_with_rate_control,
get_email_domain_part,
copy,
send_email_at_most_times,
is_valid_alias_address_domain,
should_add_dkim_signature,
add_header,
get_header_unicode,
generate_reply_email,
is_reverse_alias,
normalize_reply_email,
is_valid_email,
replace,
should_disable,
parse_id_from_bounce,
spf_pass,
sanitize_header,
get_queue_id,
should_ignore_bounce,
parse_full_address,
get_mailbox_bounce_info,
save_email_for_debugging,
save_envelope_for_debugging,
get_verp_info_from_email,
generate_verp_email,
sl_formataddr,
)
from app.errors import (
NonReverseAliasInReplyPhase,
VERPTransactional,
VERPForward,
VERPReply,
CannotCreateContactForReverseAlias,
)
from app.handler.dmarc import (
apply_dmarc_policy_for_reply_phase,
apply_dmarc_policy_for_forward_phase,
)
from app.handler.provider_complaint import (
handle_hotmail_complaint,
handle_yahoo_complaint,
)
from app.handler.spamd_result import (
SpamdResult,
SPFCheckResult,
)
from app.handler.unsubscribe_generator import UnsubscribeGenerator
from app.handler.unsubscribe_handler import UnsubscribeHandler
from app.log import LOG, set_message_id
from app.mail_sender import sl_sendmail
from app.message_utils import message_to_bytes
from app.models import (
Alias,
Contact,
BlockBehaviourEnum,
EmailLog,
User,
RefusedEmail,
Mailbox,
Bounce,
TransactionalEmail,
IgnoredEmail,
MessageIDMatching,
Notification,
VerpType,
)
from app.pgp_utils import (
PGPException,
sign_data_with_pgpy,
sign_data,
load_public_key_and_check,
)
from app.utils import sanitize_email, canonicalize_email
from init_app import load_pgp_public_keys
from server import create_light_app
def get_or_create_contact(from_header: str, mail_from: str, alias: Alias) -> Contact:
"""
contact_from_header is the RFC 2047 format FROM header
"""
try:
contact_name, contact_email = parse_full_address(from_header)
except ValueError:
contact_name, contact_email = "", ""
# Ensure contact_name is within limits
if len(contact_name) >= Contact.MAX_NAME_LENGTH:
contact_name = contact_name[0 : Contact.MAX_NAME_LENGTH]
if not is_valid_email(contact_email):
# From header is wrongly formatted, try with mail_from
if mail_from and mail_from != "<>":
LOG.w(
"Cannot parse email from from_header %s, use mail_from %s",
from_header,
mail_from,
)
contact_email = mail_from
if not is_valid_email(contact_email):
LOG.w(
"invalid contact email %s. Parse from %s %s",
contact_email,
from_header,
mail_from,
)
# either reuse a contact with empty email or create a new contact with empty email
contact_email = ""
contact_email = sanitize_email(contact_email, not_lower=True)
if contact_name and "\x00" in contact_name:
LOG.w("issue with contact name %s", contact_name)
contact_name = ""
contact = Contact.get_by(alias_id=alias.id, website_email=contact_email)
if contact:
if contact.name != contact_name:
LOG.d(
"Update contact %s name %s to %s",
contact,
contact.name,
contact_name,
)
contact.name = contact_name
Session.commit()
# contact created in the past does not have mail_from and from_header field
if not contact.mail_from and mail_from:
LOG.d(
"Set contact mail_from %s: %s to %s",
contact,
contact.mail_from,
mail_from,
)
contact.mail_from = mail_from
Session.commit()
else:
try:
contact = Contact.create(
user_id=alias.user_id,
alias_id=alias.id,
website_email=contact_email,
name=contact_name,
mail_from=mail_from,
reply_email=generate_reply_email(contact_email, alias.user)
if is_valid_email(contact_email)
else NOREPLY,
automatic_created=True,
)
if not contact_email:
LOG.d("Create a contact with invalid email for %s", alias)
contact.invalid_email = True
LOG.d(
"create contact %s for %s, reverse alias:%s",
contact_email,
alias,
contact.reply_email,
)
Session.commit()
except IntegrityError:
LOG.w("Contact %s %s already exist", alias, contact_email)
Session.rollback()
contact = Contact.get_by(alias_id=alias.id, website_email=contact_email)
return contact
def get_or_create_reply_to_contact(
reply_to_header: str, alias: Alias, msg: Message
) -> Optional[Contact]:
"""
Get or create the contact for the Reply-To header
"""
try:
contact_name, contact_address = parse_full_address(reply_to_header)
except ValueError:
return
if not is_valid_email(contact_address):
LOG.w(
"invalid reply-to address %s. Parse from %s",
contact_address,
reply_to_header,
)
return None
contact = Contact.get_by(alias_id=alias.id, website_email=contact_address)
if contact:
return contact
else:
LOG.d(
"create contact %s for alias %s via reply-to header %s",
contact_address,
alias,
reply_to_header,
)
try:
contact = Contact.create(
user_id=alias.user_id,
alias_id=alias.id,
website_email=contact_address,
name=contact_name,
reply_email=generate_reply_email(contact_address, alias.user),
automatic_created=True,
)
Session.commit()
except IntegrityError:
LOG.w("Contact %s %s already exist", alias, contact_address)
Session.rollback()
contact = Contact.get_by(alias_id=alias.id, website_email=contact_address)
return contact
def replace_header_when_forward(msg: Message, alias: Alias, header: str):
"""
Replace CC or To header by Reply emails in forward phase
"""
new_addrs: [str] = []
headers = msg.get_all(header, [])
# headers can be an array of Header, convert it to string here
headers = [get_header_unicode(h) for h in headers]
full_addresses: [EmailAddress] = []
for h in headers:
full_addresses += address.parse_list(h)
for full_address in full_addresses:
contact_email = sanitize_email(full_address.address, not_lower=True)
# no transformation when alias is already in the header
if contact_email.lower() == alias.email:
new_addrs.append(full_address.full_spec())
continue
try:
# NOT allow unicode for contact address
validate_email(
contact_email, check_deliverability=False, allow_smtputf8=False
)
except EmailNotValidError:
LOG.w("invalid contact email %s. %s. Skip", contact_email, headers)
continue
contact = Contact.get_by(alias_id=alias.id, website_email=contact_email)
if contact:
# update the contact name if needed
if contact.name != full_address.display_name:
LOG.d(
"Update contact %s name %s to %s",
contact,
contact.name,
full_address.display_name,
)
contact.name = full_address.display_name
Session.commit()
else:
LOG.d(
"create contact for alias %s and email %s, header %s",
alias,
contact_email,
header,
)
try:
contact = Contact.create(
user_id=alias.user_id,
alias_id=alias.id,
website_email=contact_email,
name=full_address.display_name,
reply_email=generate_reply_email(contact_email, alias.user),
is_cc=header.lower() == "cc",
automatic_created=True,
)
Session.commit()
except IntegrityError:
LOG.w("Contact %s %s already exist", alias, contact_email)
Session.rollback()
contact = Contact.get_by(alias_id=alias.id, website_email=contact_email)
new_addrs.append(contact.new_addr())
if new_addrs:
new_header = ",".join(new_addrs)
LOG.d("Replace %s header, old: %s, new: %s", header, msg[header], new_header)
add_or_replace_header(msg, header, new_header)
else:
LOG.d("Delete %s header, old value %s", header, msg[header])
delete_header(msg, header)
def add_alias_to_header_if_needed(msg, alias):
"""
During the forward phase, add alias to To: header if it isn't included in To and Cc header
It can happen that the alias isn't included in To: and CC: header, for example if this is a BCC email
:return:
"""
to_header = str(msg[headers.TO]) if msg[headers.TO] else None
cc_header = str(msg[headers.CC]) if msg[headers.CC] else None
# nothing to do
if to_header and alias.email in to_header:
return
# nothing to do
if cc_header and alias.email in cc_header:
return
LOG.d(f"add {alias} to To: header {to_header}")
if to_header:
add_or_replace_header(msg, headers.TO, f"{to_header},{alias.email}")
else:
add_or_replace_header(msg, headers.TO, alias.email)
def replace_header_when_reply(msg: Message, alias: Alias, header: str):
"""
Replace CC or To Reply emails by original emails
"""
new_addrs: [str] = []
headers = msg.get_all(header, [])
# headers can be an array of Header, convert it to string here
headers = [str(h) for h in headers]
# headers can contain \r or \n
headers = [h.replace("\r", "") for h in headers]
headers = [h.replace("\n", "") for h in headers]
for _, reply_email in getaddresses(headers):
# no transformation when alias is already in the header
# can happen when user clicks "Reply All"
if reply_email == alias.email:
continue
contact = Contact.get_by(reply_email=reply_email)
if not contact:
LOG.w(
"email %s contained in %s header in reply phase must be reply emails. headers:%s",
reply_email,
header,
headers,
)
raise NonReverseAliasInReplyPhase(reply_email)
# still keep this email in header
# new_addrs.append(reply_email)
else:
new_addrs.append(sl_formataddr((contact.name, contact.website_email)))
if new_addrs:
new_header = ",".join(new_addrs)
LOG.d("Replace %s header, old: %s, new: %s", header, msg[header], new_header)
add_or_replace_header(msg, header, new_header)
else:
LOG.d("delete the %s header. Old value %s", header, msg[header])
delete_header(msg, header)
def prepare_pgp_message(
orig_msg: Message, pgp_fingerprint: str, public_key: str, can_sign: bool = False
) -> Message:
msg = MIMEMultipart("encrypted", protocol="application/pgp-encrypted")
# clone orig message to avoid modifying it
clone_msg = copy(orig_msg)
# copy all headers from original message except all standard MIME headers
for i in reversed(range(len(clone_msg._headers))):
header_name = clone_msg._headers[i][0].lower()
if header_name.lower() not in headers.MIME_HEADERS:
msg[header_name] = clone_msg._headers[i][1]
# Delete unnecessary headers in clone_msg except _MIME_HEADERS to save space
delete_all_headers_except(
clone_msg,
headers.MIME_HEADERS,
)
if clone_msg[headers.CONTENT_TYPE] is None:
LOG.d("Content-Type missing")
clone_msg[headers.CONTENT_TYPE] = "text/plain"
if clone_msg[headers.MIME_VERSION] is None:
LOG.d("Mime-Version missing")
clone_msg[headers.MIME_VERSION] = "1.0"
first = MIMEApplication(
_subtype="pgp-encrypted", _encoder=encoders.encode_7or8bit, _data=""
)
first.set_payload("Version: 1")
msg.attach(first)
if can_sign and PGP_SENDER_PRIVATE_KEY:
LOG.d("Sign msg")
clone_msg = sign_msg(clone_msg)
# use pgpy as fallback
second = MIMEApplication(
"octet-stream", _encoder=encoders.encode_7or8bit, name="encrypted.asc"
)
second.add_header("Content-Disposition", 'inline; filename="encrypted.asc"')
# encrypt
# use pgpy as fallback
msg_bytes = message_to_bytes(clone_msg)
try:
encrypted_data = pgp_utils.encrypt_file(BytesIO(msg_bytes), pgp_fingerprint)
second.set_payload(encrypted_data)
except PGPException:
LOG.w(
"Cannot encrypt using python-gnupg, check if public key is valid and try with pgpy"
)
# check if the public key is valid
load_public_key_and_check(public_key)
encrypted = pgp_utils.encrypt_file_with_pgpy(msg_bytes, public_key)
second.set_payload(str(encrypted))
LOG.i(
f"encryption works with pgpy and not with python-gnupg, public key {public_key}"
)
msg.attach(second)
return msg
def sign_msg(msg: Message) -> Message:
container = MIMEMultipart(
"signed", protocol="application/pgp-signature", micalg="pgp-sha256"
)
container.attach(msg)
signature = MIMEApplication(
_subtype="pgp-signature", name="signature.asc", _data="", _encoder=encode_noop
)
signature.add_header("Content-Disposition", 'attachment; filename="signature.asc"')
try:
signature.set_payload(sign_data(message_to_bytes(msg).replace(b"\n", b"\r\n")))
except Exception:
LOG.e("Cannot sign, try using pgpy")
signature.set_payload(
sign_data_with_pgpy(message_to_bytes(msg).replace(b"\n", b"\r\n"))
)
container.attach(signature)
return container
def handle_email_sent_to_ourself(alias, from_addr: str, msg: Message, user):
# store the refused email
random_name = str(uuid.uuid4())
full_report_path = f"refused-emails/cycle-{random_name}.eml"
s3.upload_email_from_bytesio(
full_report_path, BytesIO(message_to_bytes(msg)), random_name
)
refused_email = RefusedEmail.create(
path=None, full_report_path=full_report_path, user_id=alias.user_id
)
Session.commit()
LOG.d("Create refused email %s", refused_email)
# link available for 6 days as it gets deleted in 7 days
refused_email_url = refused_email.get_url(expires_in=518400)
Notification.create(
user_id=user.id,
title=f"Email sent to {alias.email} from its own mailbox {from_addr}",
message=Notification.render(
"notification/cycle-email.html",
alias=alias,
from_addr=from_addr,
refused_email_url=refused_email_url,
),
commit=True,
)
send_email_at_most_times(
user,
ALERT_SEND_EMAIL_CYCLE,
from_addr,
f"Email sent to {alias.email} from its own mailbox {from_addr}",
render(
"transactional/cycle-email.txt.jinja2",
alias=alias,
from_addr=from_addr,
refused_email_url=refused_email_url,
),
render(
"transactional/cycle-email.html",
alias=alias,
from_addr=from_addr,
refused_email_url=refused_email_url,
),
)
def handle_forward(envelope, msg: Message, rcpt_to: str) -> List[Tuple[bool, str]]:
"""return an array of SMTP status (is_success, smtp_status)
is_success indicates whether an email has been delivered and
smtp_status is the SMTP Status ("250 Message accepted", "550 Non-existent email address", etc.)
"""
alias_address = rcpt_to # alias@SL
alias = Alias.get_by(email=alias_address)
if not alias:
LOG.d(
"alias %s not exist. Try to see if it can be created on the fly",
alias_address,
)
alias = try_auto_create(alias_address)
if not alias:
LOG.d("alias %s cannot be created on-the-fly, return 550", alias_address)
if should_ignore_bounce(envelope.mail_from):
return [(True, status.E207)]
else:
return [(False, status.E515)]
user = alias.user
if user.disabled:
LOG.w("User %s disabled, disable forwarding emails for %s", user, alias)
if should_ignore_bounce(envelope.mail_from):
return [(True, status.E207)]
else:
return [(False, status.E504)]
# check if email is sent from alias's owning mailbox(es)
mail_from = envelope.mail_from
for addr in alias.authorized_addresses():
# email sent from a mailbox to its alias
if addr == mail_from:
LOG.i("cycle email sent from %s to %s", addr, alias)
handle_email_sent_to_ourself(alias, addr, msg, user)
return [(True, status.E209)]
from_header = get_header_unicode(msg[headers.FROM])
LOG.d("Create or get contact for from_header:%s", from_header)
contact = get_or_create_contact(from_header, envelope.mail_from, alias)
reply_to_contact = None
if msg[headers.REPLY_TO]:
reply_to = get_header_unicode(msg[headers.REPLY_TO])
LOG.d("Create or get contact for reply_to_header:%s", reply_to)
# ignore when reply-to = alias
if reply_to == alias.email:
LOG.i("Reply-to same as alias %s", alias)
else:
reply_to_contact = get_or_create_reply_to_contact(reply_to, alias, msg)
if not alias.enabled or contact.block_forward:
LOG.d("%s is disabled, do not forward", alias)
EmailLog.create(
contact_id=contact.id,
user_id=contact.user_id,
blocked=True,
alias_id=contact.alias_id,
commit=True,
)
# by default return 2** instead of 5** to allow user to receive emails again
# when alias is enabled or contact is unblocked
res_status = status.E200
if user.block_behaviour == BlockBehaviourEnum.return_5xx:
res_status = status.E502
return [(True, res_status)]
# Check if we need to reject or quarantine based on dmarc
msg, dmarc_delivery_status = apply_dmarc_policy_for_forward_phase(
alias, contact, envelope, msg
)
if dmarc_delivery_status is not None:
return [(False, dmarc_delivery_status)]
ret = []
mailboxes = alias.mailboxes
# no valid mailbox
if not mailboxes:
LOG.w("no valid mailboxes for %s", alias)
if should_ignore_bounce(envelope.mail_from):
return [(True, status.E207)]
else:
return [(False, status.E516)]
for mailbox in mailboxes:
if not mailbox.verified:
LOG.d("%s unverified, do not forward", mailbox)
ret.append((False, status.E517))
else:
# Check if the mailbox is also an alias and stop the loop
mailbox_as_alias = Alias.get_by(email=mailbox.email)
if mailbox_as_alias is not None:
LOG.info(
f"Mailbox {mailbox.id} has email {mailbox.email} that is also alias {alias.id}. Stopping loop"
)
mailbox.verified = False
Session.commit()
mailbox_url = f"{URL}/dashboard/mailbox/{mailbox.id}/"
send_email_with_rate_control(
user,
ALERT_MAILBOX_IS_ALIAS,
user.email,
f"Your mailbox {mailbox.email} is an alias",
render(
"transactional/mailbox-invalid.txt.jinja2",
mailbox=mailbox,
mailbox_url=mailbox_url,
alias=alias,
),
render(
"transactional/mailbox-invalid.html",
mailbox=mailbox,
mailbox_url=mailbox_url,
alias=alias,
),
max_nb_alert=1,
)
ret.append((False, status.E525))
continue
# create a copy of message for each forward
ret.append(
forward_email_to_mailbox(
alias, copy(msg), contact, envelope, mailbox, user, reply_to_contact
)
)
return ret
def forward_email_to_mailbox(
alias,
msg: Message,
contact: Contact,
envelope,
mailbox,
user,
reply_to_contact: Optional[Contact],
) -> (bool, str):
LOG.d("Forward %s -> %s -> %s", contact, alias, mailbox)
if mailbox.disabled:
LOG.d("%s disabled, do not forward")
if should_ignore_bounce(envelope.mail_from):
return True, status.E207
else:
return False, status.E518
# sanity check: make sure mailbox is not actually an alias
if get_email_domain_part(alias.email) == get_email_domain_part(mailbox.email):
LOG.w(
"Mailbox has the same domain as alias. %s -> %s -> %s",
contact,
alias,
mailbox,
)
mailbox_url = f"{URL}/dashboard/mailbox/{mailbox.id}/"
send_email_with_rate_control(
user,
ALERT_MAILBOX_IS_ALIAS,
user.email,
f"Your mailbox {mailbox.email} and alias {alias.email} use the same domain",
render(
"transactional/mailbox-invalid.txt.jinja2",
mailbox=mailbox,
mailbox_url=mailbox_url,
alias=alias,
),
render(
"transactional/mailbox-invalid.html",
mailbox=mailbox,
mailbox_url=mailbox_url,
alias=alias,
),
max_nb_alert=1,
)
# retry later
# so when user fixes the mailbox, the email can be delivered
return False, status.E405
email_log = EmailLog.create(
contact_id=contact.id,
user_id=user.id,
mailbox_id=mailbox.id,
alias_id=contact.alias_id,
message_id=str(msg[headers.MESSAGE_ID]),
commit=True,
)
LOG.d("Create %s for %s, %s, %s", email_log, contact, user, mailbox)
if ENABLE_SPAM_ASSASSIN:
# Spam check
spam_status = ""
is_spam = False
if SPAMASSASSIN_HOST:
start = time.time()
spam_score, spam_report = get_spam_score(msg, email_log)
LOG.d(
"%s -> %s - spam score:%s in %s seconds. Spam report %s",
contact,
alias,
spam_score,
time.time() - start,
spam_report,
)
email_log.spam_score = spam_score
Session.commit()
if (user.max_spam_score and spam_score > user.max_spam_score) or (
not user.max_spam_score and spam_score > MAX_SPAM_SCORE
):
is_spam = True
# only set the spam report for spam
email_log.spam_report = spam_report
else:
is_spam, spam_status = get_spam_info(msg, max_score=user.max_spam_score)
if is_spam:
LOG.w(
"Email detected as spam. %s -> %s. Spam Score: %s, Spam Report: %s",
contact,
alias,
email_log.spam_score,
email_log.spam_report,
)
email_log.is_spam = True
email_log.spam_status = spam_status
Session.commit()
handle_spam(contact, alias, msg, user, mailbox, email_log)
return False, status.E519
if contact.invalid_email:
LOG.d("add noreply information %s %s", alias, mailbox)
msg = add_header(
msg,
f"""Email sent to {alias.email} from an invalid address and cannot be replied""",
f"""Email sent to {alias.email} from an invalid address and cannot be replied""",
)
delete_all_headers_except(
msg,
[
headers.FROM,
headers.TO,
headers.CC,
headers.SUBJECT,
headers.DATE,
# do not delete original message id
headers.MESSAGE_ID,
# References and In-Reply-To are used for keeping the email thread
headers.REFERENCES,
headers.IN_REPLY_TO,
]
+ headers.MIME_HEADERS,
)
# create PGP email if needed
if mailbox.pgp_enabled() and user.is_premium() and not alias.disable_pgp:
LOG.d("Encrypt message using mailbox %s", mailbox)
if mailbox.generic_subject:
LOG.d("Use a generic subject for %s", mailbox)
orig_subject = msg[headers.SUBJECT]
orig_subject = get_header_unicode(orig_subject)
add_or_replace_header(msg, "Subject", mailbox.generic_subject)
sender = msg[headers.FROM]
sender = get_header_unicode(sender)
msg = add_header(
msg,
f"""Forwarded by SimpleLogin to {alias.email} from "{sender}" with "{orig_subject}" as subject""",
f"""Forwarded by SimpleLogin to {alias.email} from "{sender}" with <b>{orig_subject}</b> as subject""",
)
try:
msg = prepare_pgp_message(
msg, mailbox.pgp_finger_print, mailbox.pgp_public_key, can_sign=True
)
except PGPException:
LOG.w(
"Cannot encrypt message %s -> %s. %s %s", contact, alias, mailbox, user
)
msg = add_header(
msg,
f"""PGP encryption fails with {mailbox.email}'s PGP key""",
)
# add custom header
add_or_replace_header(msg, headers.SL_DIRECTION, "Forward")
msg[headers.SL_EMAIL_LOG_ID] = str(email_log.id)
if user.include_header_email_header:
msg[headers.SL_ENVELOPE_FROM] = envelope.mail_from
# when an alias isn't in the To: header, there's no way for users to know what alias has received the email
msg[headers.SL_ENVELOPE_TO] = alias.email
if not msg[headers.DATE]:
LOG.w("missing date header, create one")
msg[headers.DATE] = formatdate()
replace_sl_message_id_by_original_message_id(msg)
# change the from_header so the email comes from a reverse-alias
# replace the email part in from: header
old_from_header = msg[headers.FROM]
new_from_header = contact.new_addr()
add_or_replace_header(msg, "From", new_from_header)
LOG.d("From header, new:%s, old:%s", new_from_header, old_from_header)
if reply_to_contact:
reply_to_header = msg[headers.REPLY_TO]
new_reply_to_header = reply_to_contact.new_addr()
add_or_replace_header(msg, "Reply-To", new_reply_to_header)
LOG.d("Reply-To header, new:%s, old:%s", new_reply_to_header, reply_to_header)
# replace CC & To emails by reverse-alias for all emails that are not alias
try:
replace_header_when_forward(msg, alias, headers.CC)
replace_header_when_forward(msg, alias, headers.TO)
except CannotCreateContactForReverseAlias:
LOG.d("CannotCreateContactForReverseAlias error, delete %s", email_log)
EmailLog.delete(email_log.id)
Session.commit()
raise
# add alias to To: header if it isn't included in To and Cc header
add_alias_to_header_if_needed(msg, alias)
# add List-Unsubscribe header
msg = UnsubscribeGenerator().add_header_to_message(alias, contact, msg)
add_dkim_signature(msg, EMAIL_DOMAIN)
LOG.d(
"Forward mail from %s to %s, mail_options:%s, rcpt_options:%s ",
contact.website_email,
mailbox.email,
envelope.mail_options,
envelope.rcpt_options,
)
try:
sl_sendmail(
# use a different envelope sender for each forward (aka VERP)
generate_verp_email(VerpType.bounce_forward, email_log.id),
mailbox.email,
msg,
envelope.mail_options,
envelope.rcpt_options,
is_forward=True,
)
except (SMTPServerDisconnected, SMTPRecipientsRefused, TimeoutError):
LOG.w(
"Postfix error during forward phase %s -> %s -> %s",
contact,
alias,
mailbox,
exc_info=True,
)
if should_ignore_bounce(envelope.mail_from):
return True, status.E207
else:
EmailLog.delete(email_log.id, commit=True)
# so Postfix can retry
return False, status.E407
else:
Session.commit()
return True, status.E200
def replace_sl_message_id_by_original_message_id(msg):
# Replace SL Message-ID by original one in In-Reply-To header
if msg[headers.IN_REPLY_TO]:
matching: MessageIDMatching = MessageIDMatching.get_by(
sl_message_id=str(msg[headers.IN_REPLY_TO])
)
if matching:
LOG.d(
"replace SL message id by original one in in-reply-to header, %s -> %s",
msg[headers.IN_REPLY_TO],
matching.original_message_id,
)
del msg[headers.IN_REPLY_TO]
msg[headers.IN_REPLY_TO] = matching.original_message_id
# Replace SL Message-ID by original Message-ID in References header
if msg[headers.REFERENCES]:
message_ids = str(msg[headers.REFERENCES]).split()
new_message_ids = []
for message_id in message_ids:
matching = MessageIDMatching.get_by(sl_message_id=message_id)
if matching:
LOG.d(
"replace SL message id by original one in references header, %s -> %s",
message_id,
matching.original_message_id,
)
new_message_ids.append(matching.original_message_id)
else:
new_message_ids.append(message_id)
del msg[headers.REFERENCES]
msg[headers.REFERENCES] = " ".join(new_message_ids)
def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
"""
Return whether an email has been delivered and
the smtp status ("250 Message accepted", "550 Non-existent email address", etc)
"""
reply_email = rcpt_to
# reply_email must end with EMAIL_DOMAIN
if not reply_email.endswith(EMAIL_DOMAIN):
LOG.w(f"Reply email {reply_email} has wrong domain")
return False, status.E501
# handle case where reply email is generated with non-allowed char
reply_email = normalize_reply_email(reply_email)
contact = Contact.get_by(reply_email=reply_email)
if not contact:
LOG.w(f"No contact with {reply_email} as reverse alias")
return False, status.E502
alias = contact.alias
alias_address: str = contact.alias.email
alias_domain = alias_address[alias_address.find("@") + 1 :]
# Sanity check: verify alias domain is managed by SimpleLogin
# scenario: a user have removed a domain but due to a bug, the aliases are still there
if not is_valid_alias_address_domain(alias.email):
LOG.e("%s domain isn't known", alias)
return False, status.E503
user = alias.user
mail_from = envelope.mail_from
if user.disabled:
LOG.e(
"User %s disabled, disable sending emails from %s to %s",
user,
alias,
contact,
)
return False, status.E504
# Check if we need to reject or quarantine based on dmarc
dmarc_delivery_status = apply_dmarc_policy_for_reply_phase(
alias, contact, envelope, msg
)
if dmarc_delivery_status is not None:
return False, dmarc_delivery_status
# Anti-spoofing
mailbox = get_mailbox_from_mail_from(mail_from, alias)
if not mailbox:
if alias.disable_email_spoofing_check:
# ignore this error, use default alias mailbox
LOG.w(
"ignore unknown sender to reverse-alias %s: %s -> %s",
mail_from,
alias,
contact,
)
mailbox = alias.mailbox
else:
# only mailbox can send email to the reply-email
handle_unknown_mailbox(envelope, msg, reply_email, user, alias, contact)
# return 2** to avoid Postfix sending out bounces and avoid backscatter issue
return False, status.E214
if ENFORCE_SPF and mailbox.force_spf and not alias.disable_email_spoofing_check:
if not spf_pass(envelope, mailbox, user, alias, contact.website_email, msg):
# cannot use 4** here as sender will retry.
# cannot use 5** because that generates bounce report
return True, status.E201
email_log = EmailLog.create(
contact_id=contact.id,
alias_id=contact.alias_id,
is_reply=True,
user_id=contact.user_id,
mailbox_id=mailbox.id,
message_id=msg[headers.MESSAGE_ID],
commit=True,
)
LOG.d("Create %s for %s, %s, %s", email_log, contact, user, mailbox)
# Spam check
if ENABLE_SPAM_ASSASSIN:
spam_status = ""
is_spam = False
# do not use user.max_spam_score here
if SPAMASSASSIN_HOST:
start = time.time()
spam_score, spam_report = get_spam_score(msg, email_log)
LOG.d(
"%s -> %s - spam score %s in %s seconds. Spam report %s",
alias,
contact,
spam_score,
time.time() - start,
spam_report,
)
email_log.spam_score = spam_score
if spam_score > MAX_REPLY_PHASE_SPAM_SCORE:
is_spam = True
# only set the spam report for spam
email_log.spam_report = spam_report
else:
is_spam, spam_status = get_spam_info(
msg, max_score=MAX_REPLY_PHASE_SPAM_SCORE
)
if is_spam:
LOG.w(
"Email detected as spam. Reply phase. %s -> %s. Spam Score: %s, Spam Report: %s",
alias,
contact,
email_log.spam_score,
email_log.spam_report,
)
email_log.is_spam = True
email_log.spam_status = spam_status
Session.commit()
handle_spam(contact, alias, msg, user, mailbox, email_log, is_reply=True)
return False, status.E506
delete_all_headers_except(
msg,
[
headers.FROM,
headers.TO,
headers.CC,
headers.SUBJECT,
headers.DATE,
# do not delete original message id
headers.MESSAGE_ID,
# References and In-Reply-To are used for keeping the email thread
headers.REFERENCES,
headers.IN_REPLY_TO,
]
+ headers.MIME_HEADERS,
)
orig_to = msg[headers.TO]
orig_cc = msg[headers.CC]
# replace the reverse-alias by the contact email in the email body
# as this is usually included when replying
if user.replace_reverse_alias:
LOG.d("Replace reverse-alias %s by contact email %s", reply_email, contact)
msg = replace(msg, reply_email, contact.website_email)
LOG.d("Replace mailbox %s by alias email %s", mailbox.email, alias.email)
msg = replace(msg, mailbox.email, alias.email)
if config.ENABLE_ALL_REVERSE_ALIAS_REPLACEMENT:
start = time.time()
# MAX_NB_REVERSE_ALIAS_REPLACEMENT is there to limit potential attack
contact_query = (
Contact.query()
.filter(Contact.alias_id == alias.id)
.limit(config.MAX_NB_REVERSE_ALIAS_REPLACEMENT)
)
# replace reverse alias by real address for all contacts
for (reply_email, website_email) in contact_query.values(
Contact.reply_email, Contact.website_email
):
msg = replace(msg, reply_email, website_email)
elapsed = time.time() - start
LOG.d(
"Replace reverse alias by real address for %s contacts takes %s seconds",
contact_query.count(),
elapsed,
)
newrelic.agent.record_custom_metric(
"Custom/reverse_alias_replacement_time", elapsed
)
# create PGP email if needed
if contact.pgp_finger_print and user.is_premium():
LOG.d("Encrypt message for contact %s", contact)
try:
msg = prepare_pgp_message(
msg, contact.pgp_finger_print, contact.pgp_public_key
)
except PGPException:
LOG.e(
"Cannot encrypt message %s -> %s. %s %s", alias, contact, mailbox, user
)
# programming error, user shouldn't see a new email log
EmailLog.delete(email_log.id, commit=True)
# return 421 so the client can retry later
return False, status.E402
Session.commit()
# make the email comes from alias
from_header = alias.email
# add alias name from alias
if alias.name:
LOG.d("Put alias name %s in from header", alias.name)
from_header = sl_formataddr((alias.name, alias.email))
elif alias.custom_domain:
# add alias name from domain
if alias.custom_domain.name:
LOG.d(
"Put domain default alias name %s in from header",
alias.custom_domain.name,
)
from_header = sl_formataddr((alias.custom_domain.name, alias.email))
LOG.d("From header is %s", from_header)
add_or_replace_header(msg, headers.FROM, from_header)
try:
if str(msg[headers.TO]).lower() == "undisclosed-recipients:;":
# no need to replace TO header
LOG.d("email is sent in BCC mode")
del msg[headers.TO]
else:
replace_header_when_reply(msg, alias, headers.TO)
replace_header_when_reply(msg, alias, headers.CC)
except NonReverseAliasInReplyPhase as e:
LOG.w("non reverse-alias in reply %s %s %s", e, contact, alias)
# the email is ignored, delete the email log
EmailLog.delete(email_log.id, commit=True)
send_email(
mailbox.email,
f"Email sent to {contact.email} contains non reverse-alias addresses",
render(
"transactional/non-reverse-alias-reply-phase.txt.jinja2",
destination=contact.email,
alias=alias.email,
subject=msg[headers.SUBJECT],
),
)
# user is informed and will retry
return True, status.E200
replace_original_message_id(alias, email_log, msg)
if not msg[headers.DATE]:
date_header = formatdate()
LOG.w("missing date header, add one")
msg[headers.DATE] = date_header
msg[headers.SL_DIRECTION] = "Reply"
msg[headers.SL_EMAIL_LOG_ID] = str(email_log.id)
LOG.d(
"send email from %s to %s, mail_options:%s,rcpt_options:%s",
alias.email,
contact.website_email,
envelope.mail_options,
envelope.rcpt_options,
)
if should_add_dkim_signature(alias_domain):
add_dkim_signature(msg, alias_domain)
try:
sl_sendmail(
generate_verp_email(VerpType.bounce_reply, email_log.id, alias_domain),
contact.website_email,
msg,
envelope.mail_options,
envelope.rcpt_options,
is_forward=False,
)
# if alias belongs to several mailboxes, notify other mailboxes about this email
other_mailboxes = [mb for mb in alias.mailboxes if mb.email != mailbox.email]
for mb in other_mailboxes:
notify_mailbox(alias, mailbox, mb, msg, orig_to, orig_cc, alias_domain)
except Exception:
LOG.w("Cannot send email from %s to %s", alias, contact)
EmailLog.delete(email_log.id, commit=True)
send_email(
mailbox.email,
f"Email cannot be sent to {contact.email} from {alias.email}",
render(
"transactional/reply-error.txt.jinja2",
user=user,
alias=alias,
contact=contact,
contact_domain=get_email_domain_part(contact.email),
),
render(
"transactional/reply-error.html",
user=user,
alias=alias,
contact=contact,
contact_domain=get_email_domain_part(contact.email),
),
)
# return 250 even if error as user is already informed of the incident and can retry sending the email
return True, status.E200
def notify_mailbox(
alias, mailbox, other_mb: Mailbox, msg, orig_to, orig_cc, alias_domain
):
"""Notify another mailbox about an email sent by a mailbox to a reverse alias"""
LOG.d(
f"notify {other_mb.email} about email sent "
f"from {mailbox.email} on behalf of {alias.email} to {msg[headers.TO]}"
)
notif = add_header(
msg,
f"""**** Don't forget to remove this section if you reply to this email ****
Email sent on behalf of alias {alias.email} using mailbox {mailbox.email}""",
)
# use alias as From to hint that the email is sent from the alias
add_or_replace_header(notif, headers.FROM, alias.email)
# keep the reverse alias in CC and To header so user can reply more easily
add_or_replace_header(notif, headers.TO, orig_to)
add_or_replace_header(notif, headers.CC, orig_cc)
# add DKIM as the email is sent from alias
if should_add_dkim_signature(alias_domain):
add_dkim_signature(msg, alias_domain)
# this notif is considered transactional email
transaction = TransactionalEmail.create(email=other_mb.email, commit=True)
sl_sendmail(
generate_verp_email(VerpType.transactional, transaction.id, alias_domain),
other_mb.email,
notif,
)
def replace_original_message_id(alias: Alias, email_log: EmailLog, msg: Message):
"""
Replace original Message-ID by SL-Message-ID during the reply phase
for "message-id" and "References" headers
"""
original_message_id = msg[headers.MESSAGE_ID]
if original_message_id:
matching = MessageIDMatching.get_by(original_message_id=original_message_id)
# can happen when a user replies to multiple recipient from their alias
# a SL Message_id will be created for the first recipient
# it should be reused for other recipients
if matching:
sl_message_id = matching.sl_message_id
LOG.d("reuse the sl_message_id %s", sl_message_id)
else:
sl_message_id = make_msgid(
str(email_log.id), get_email_domain_part(alias.email)
)
LOG.d("create a new sl_message_id %s", sl_message_id)
try:
MessageIDMatching.create(
sl_message_id=sl_message_id,
original_message_id=original_message_id,
email_log_id=email_log.id,
commit=True,
)
except IntegrityError:
LOG.w(
"another matching with original_message_id %s was created in the mean time",
original_message_id,
)
Session.rollback()
matching = MessageIDMatching.get_by(
original_message_id=original_message_id
)
sl_message_id = matching.sl_message_id
else:
sl_message_id = make_msgid(
str(email_log.id), get_email_domain_part(alias.email)
)
LOG.d("no original_message_id, create a new sl_message_id %s", sl_message_id)
del msg[headers.MESSAGE_ID]
msg[headers.MESSAGE_ID] = sl_message_id
email_log.sl_message_id = sl_message_id
Session.commit()
# Replace all original headers in References header by SL Message ID header if needed
if msg[headers.REFERENCES]:
message_ids = str(msg[headers.REFERENCES]).split()
new_message_ids = []
for message_id in message_ids:
matching = MessageIDMatching.get_by(original_message_id=message_id)
if matching:
LOG.d(
"replace original message id by SL one, %s -> %s",
message_id,
matching.sl_message_id,
)
new_message_ids.append(matching.sl_message_id)
else:
new_message_ids.append(message_id)
del msg[headers.REFERENCES]
msg[headers.REFERENCES] = " ".join(new_message_ids)
def get_mailbox_from_mail_from(mail_from: str, alias) -> Optional[Mailbox]:
"""return the corresponding mailbox given the mail_from and alias
Usually the mail_from=mailbox.email but it can also be one of the authorized address
"""
def __check(email_address: str, alias: Alias) -> Optional[Mailbox]:
for mailbox in alias.mailboxes:
if mailbox.email == email_address:
return mailbox
for authorized_address in mailbox.authorized_addresses:
if authorized_address.email == email_address:
LOG.d(
"Found an authorized address for %s %s %s",
alias,
mailbox,
authorized_address,
)
return mailbox
return None
# We need to first check for the uncanonicalized version because we still have users in the db with the
# email non canonicalized. So if it matches the already existing one use that, otherwise check the canonical one
return __check(mail_from, alias) or __check(canonicalize_email(mail_from), alias)
def handle_unknown_mailbox(
envelope, msg, reply_email: str, user: User, alias: Alias, contact: Contact
):
LOG.w(
"Reply email can only be used by mailbox. "
"Actual mail_from: %s. msg from header: %s, reverse-alias %s, %s %s %s",
envelope.mail_from,
msg[headers.FROM],
reply_email,
alias,
user,
contact,
)
authorize_address_link = (
f"{URL}/dashboard/mailbox/{alias.mailbox_id}/#authorized-address"
)
mailbox_emails = [mailbox.email for mailbox in alias.mailboxes]
send_email_with_rate_control(
user,
ALERT_REVERSE_ALIAS_UNKNOWN_MAILBOX,
user.email,
f"Attempt to use your alias {alias.email} from {envelope.mail_from}",
render(
"transactional/reply-must-use-personal-email.txt",
alias=alias,
sender=envelope.mail_from,
authorize_address_link=authorize_address_link,
mailbox_emails=mailbox_emails,
),
render(
"transactional/reply-must-use-personal-email.html",
alias=alias,
sender=envelope.mail_from,
authorize_address_link=authorize_address_link,
mailbox_emails=mailbox_emails,
),
)
def handle_bounce_forward_phase(msg: Message, email_log: EmailLog):
"""
Handle forward phase bounce
Happens when an email cannot be sent to a mailbox
"""
contact = email_log.contact
alias = contact.alias
user = alias.user
mailbox = email_log.mailbox
# email_log.mailbox should be set during the forward phase
if not mailbox:
LOG.e("Use %s default mailbox %s", alias, alias.mailbox)
mailbox = alias.mailbox
bounce_info = get_mailbox_bounce_info(msg)
if bounce_info:
Bounce.create(
email=mailbox.email, info=bounce_info.as_bytes().decode(), commit=True
)
else:
LOG.w("cannot get bounce info, debug at %s", save_email_for_debugging(msg))
Bounce.create(email=mailbox.email, commit=True)
LOG.d(
"Handle forward bounce %s -> %s -> %s. %s", contact, alias, mailbox, email_log
)
# Store the bounced email, generate a name for the email
random_name = str(uuid.uuid4())
full_report_path = f"refused-emails/full-{random_name}.eml"
s3.upload_email_from_bytesio(
full_report_path, BytesIO(message_to_bytes(msg)), f"full-{random_name}"
)
file_path = None
orig_msg = get_orig_message_from_bounce(msg)
if not orig_msg:
# Some MTA does not return the original message in bounce message
# nothing we can do here
LOG.w(
"Cannot parse original message from bounce message %s %s %s %s",
alias,
user,
contact,
full_report_path,
)
else:
file_path = f"refused-emails/{random_name}.eml"
s3.upload_email_from_bytesio(
file_path, BytesIO(message_to_bytes(orig_msg)), random_name
)
refused_email = RefusedEmail.create(
path=file_path, full_report_path=full_report_path, user_id=user.id
)
Session.flush()
LOG.d("Create refused email %s", refused_email)
email_log.bounced = True
email_log.refused_email_id = refused_email.id
email_log.bounced_mailbox_id = mailbox.id
Session.commit()
refused_email_url = f"{URL}/dashboard/refused_email?highlight_id={email_log.id}"
alias_will_be_disabled, reason = should_disable(alias)
if alias_will_be_disabled:
LOG.w(
f"Disable alias {alias} because {reason}. {alias.mailboxes} {alias.user}. Last contact {contact}"
)
alias.enabled = False
Notification.create(
user_id=user.id,
title=f"{alias.email} has been disabled due to multiple bounces",
message=Notification.render(
"notification/alias-disable.html", alias=alias, mailbox=mailbox
),
)
Session.commit()
send_email_with_rate_control(
user,
ALERT_BOUNCE_EMAIL,
user.email,
f"Alias {alias.email} has been disabled due to multiple bounces",
render(
"transactional/bounce/automatic-disable-alias.txt",
alias=alias,
refused_email_url=refused_email_url,
mailbox_email=mailbox.email,
),
render(
"transactional/bounce/automatic-disable-alias.html",
alias=alias,
refused_email_url=refused_email_url,
mailbox_email=mailbox.email,
),
max_nb_alert=10,
ignore_smtp_error=True,
)
else:
LOG.d(
"Inform user %s about a bounce from contact %s to alias %s",
user,
contact,
alias,
)
disable_alias_link = f"{URL}/dashboard/unsubscribe/{alias.id}"
block_sender_link = f"{URL}/dashboard/alias_contact_manager/{alias.id}?highlight_contact_id={contact.id}"
Notification.create(
user_id=user.id,
title=f"Email from {contact.website_email} to {alias.email} cannot be delivered to {mailbox.email}",
message=Notification.render(
"notification/bounce-forward-phase.html",
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email.get_url(),
mailbox_email=mailbox.email,
block_sender_link=block_sender_link,
),
commit=True,
)
send_email_with_rate_control(
user,
ALERT_BOUNCE_EMAIL,
user.email,
f"An email sent to {alias.email} cannot be delivered to your mailbox",
render(
"transactional/bounce/bounced-email.txt.jinja2",
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
block_sender_link=block_sender_link,
refused_email_url=refused_email_url,
mailbox_email=mailbox.email,
),
render(
"transactional/bounce/bounced-email.html",
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
mailbox_email=mailbox.email,
),
max_nb_alert=10,
# smtp error can happen if user mailbox is unreachable, that might explain the bounce
ignore_smtp_error=True,
)
def handle_bounce_reply_phase(envelope, msg: Message, email_log: EmailLog):
"""
Handle reply phase bounce
Happens when an email cannot be sent from an alias to a contact
"""
contact: Contact = email_log.contact
alias = contact.alias
user = alias.user
mailbox = email_log.mailbox or alias.mailbox
LOG.d("Handle reply bounce %s -> %s -> %s.%s", mailbox, alias, contact, email_log)
bounce_info = get_mailbox_bounce_info(msg)
if bounce_info:
Bounce.create(
email=sanitize_email(contact.website_email, not_lower=True),
info=bounce_info.as_bytes().decode(),
commit=True,
)
else:
LOG.w("cannot get bounce info, debug at %s", save_email_for_debugging(msg))
Bounce.create(
email=sanitize_email(contact.website_email, not_lower=True), commit=True
)
# Store the bounced email
# generate a name for the email
random_name = str(uuid.uuid4())
full_report_path = f"refused-emails/full-{random_name}.eml"
s3.upload_email_from_bytesio(
full_report_path, BytesIO(message_to_bytes(msg)), random_name
)
orig_msg = get_orig_message_from_bounce(msg)
file_path = None
if orig_msg:
file_path = f"refused-emails/{random_name}.eml"
s3.upload_email_from_bytesio(
file_path, BytesIO(message_to_bytes(orig_msg)), random_name
)
refused_email = RefusedEmail.create(
path=file_path, full_report_path=full_report_path, user_id=user.id, commit=True
)
LOG.d("Create refused email %s", refused_email)
email_log.bounced = True
email_log.refused_email_id = refused_email.id
email_log.bounced_mailbox_id = mailbox.id
Session.commit()
refused_email_url = f"{URL}/dashboard/refused_email?highlight_id={email_log.id}"
LOG.d(
"Inform user %s about bounced email sent by %s to %s",
user,
alias,
contact,
)
Notification.create(
user_id=user.id,
title=f"Email cannot be sent to { contact.email } from your alias { alias.email }",
message=Notification.render(
"notification/bounce-reply-phase.html",
alias=alias,
contact=contact,
refused_email_url=refused_email.get_url(),
),
commit=True,
)
send_email_with_rate_control(
user,
ALERT_BOUNCE_EMAIL_REPLY_PHASE,
mailbox.email,
f"Email cannot be sent to { contact.email } from your alias { alias.email }",
render(
"transactional/bounce/bounce-email-reply-phase.txt",
alias=alias,
contact=contact,
refused_email_url=refused_email_url,
),
render(
"transactional/bounce/bounce-email-reply-phase.html",
alias=alias,
contact=contact,
refused_email_url=refused_email_url,
),
)
def handle_spam(
contact: Contact,
alias: Alias,
msg: Message,
user: User,
mailbox: Mailbox,
email_log: EmailLog,
is_reply=False, # whether the email is in forward or reply phase
):
# Store the report & original email
orig_msg = get_orig_message_from_spamassassin_report(msg)
# generate a name for the email
random_name = str(uuid.uuid4())
full_report_path = f"spams/full-{random_name}.eml"
s3.upload_email_from_bytesio(
full_report_path, BytesIO(message_to_bytes(msg)), random_name
)
file_path = None
if orig_msg:
file_path = f"spams/{random_name}.eml"
s3.upload_email_from_bytesio(
file_path, BytesIO(message_to_bytes(orig_msg)), random_name
)
refused_email = RefusedEmail.create(
path=file_path, full_report_path=full_report_path, user_id=user.id
)
Session.flush()
email_log.refused_email_id = refused_email.id
Session.commit()
LOG.d("Create spam email %s", refused_email)
refused_email_url = f"{URL}/dashboard/refused_email?highlight_id={email_log.id}"
disable_alias_link = f"{URL}/dashboard/unsubscribe/{alias.id}"
if is_reply:
LOG.d(
"Inform %s (%s) about spam email sent from alias %s to %s. %s",
mailbox,
user,
alias,
contact,
refused_email,
)
send_email_with_rate_control(
user,
ALERT_SPAM_EMAIL,
mailbox.email,
f"Email from {alias.email} to {contact.website_email} is detected as spam",
render(
"transactional/spam-email-reply-phase.txt",
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
),
render(
"transactional/spam-email-reply-phase.html",
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
),
)
else:
# inform user
LOG.d(
"Inform %s (%s) about spam email sent by %s to alias %s",
mailbox,
user,
contact,
alias,
)
send_email_with_rate_control(
user,
ALERT_SPAM_EMAIL,
mailbox.email,
f"Email from {contact.website_email} to {alias.email} is detected as spam",
render(
"transactional/spam-email.txt",
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
),
render(
"transactional/spam-email.html",
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
),
)
def is_automatic_out_of_office(msg: Message) -> bool:
"""
Return whether an email is out-of-office
For info, out-of-office is sent to the envelope mail_from and not the From: header
More info on https://datatracker.ietf.org/doc/html/rfc3834#section-4 and https://support.google.com/mail/thread/21246740/my-auto-reply-filter-isn-t-replying-to-original-sender-address?hl=en&msgid=21261237
"""
if msg[headers.AUTO_SUBMITTED] is None:
return False
if msg[headers.AUTO_SUBMITTED].lower() in ("auto-replied", "auto-generated"):
LOG.d(
"out-of-office email %s:%s",
headers.AUTO_SUBMITTED,
msg[headers.AUTO_SUBMITTED],
)
return True
return False
def is_bounce(envelope: Envelope, msg: Message):
"""Detect whether an email is a Delivery Status Notification"""
return (
envelope.mail_from == "<>"
and msg.get_content_type().lower() == "multipart/report"
)
def handle_transactional_bounce(
envelope: Envelope, msg, rcpt_to, transactional_id=None
):
LOG.d("handle transactional bounce sent to %s", rcpt_to)
# parse the TransactionalEmail
transactional_id = transactional_id or parse_id_from_bounce(rcpt_to)
transactional = TransactionalEmail.get(transactional_id)
# a transaction might have been deleted in delete_logs()
if transactional:
LOG.i("Create bounce for %s", transactional.email)
bounce_info = get_mailbox_bounce_info(msg)
if bounce_info:
Bounce.create(
email=transactional.email,
info=bounce_info.as_bytes().decode(),
commit=True,
)
else:
LOG.w("cannot get bounce info, debug at %s", save_email_for_debugging(msg))
Bounce.create(email=transactional.email, commit=True)
def handle_bounce(envelope, email_log: EmailLog, msg: Message) -> str:
"""
Return SMTP status, e.g. "500 Error"
"""
if not email_log:
LOG.w("No such email log")
return status.E512
contact: Contact = email_log.contact
alias = contact.alias
LOG.d(
"handle bounce for %s, phase=%s, contact=%s, alias=%s",
email_log,
email_log.get_phase(),
contact,
alias,
)
if email_log.is_reply:
content_type = msg.get_content_type().lower()
if content_type != "multipart/report" or envelope.mail_from != "<>":
# forward the email again to the alias
LOG.i(
"Handle auto reply %s %s",
content_type,
envelope.mail_from,
)
contact: Contact = email_log.contact
alias = contact.alias
email_log.auto_replied = True
Session.commit()
# replace the BOUNCE_EMAIL by alias in To field
add_or_replace_header(msg, "To", alias.email)
envelope.rcpt_tos = [alias.email]
# same as handle()
# result of all deliveries
# each element is a couple of whether the delivery is successful and the smtp status
res: [(bool, str)] = []
for is_delivered, smtp_status in handle_forward(envelope, msg, alias.email):
res.append((is_delivered, smtp_status))
for (is_success, smtp_status) in res:
# Consider all deliveries successful if 1 delivery is successful
if is_success:
return smtp_status
# Failed delivery for all, return the first failure
return res[0][1]
handle_bounce_reply_phase(envelope, msg, email_log)
return status.E212
else: # forward phase
handle_bounce_forward_phase(msg, email_log)
return status.E211
def should_ignore(mail_from: str, rcpt_tos: List[str]) -> bool:
if len(rcpt_tos) != 1:
return False
rcpt_to = rcpt_tos[0]
if IgnoredEmail.get_by(mail_from=mail_from, rcpt_to=rcpt_to):
return True
return False
def send_no_reply_response(mail_from: str, msg: Message):
mailbox = Mailbox.get_by(email=mail_from)
if not mailbox:
LOG.d("Unknown sender. Skipping reply from {}".format(NOREPLY))
return
send_email_at_most_times(
mailbox.user,
ALERT_TO_NOREPLY,
mailbox.user.email,
"Auto: {}".format(msg[headers.SUBJECT] or "No subject"),
render("transactional/noreply.text.jinja2"),
)
def handle(envelope: Envelope, msg: Message) -> str:
"""Return SMTP status"""
# sanitize mail_from, rcpt_tos
mail_from = sanitize_email(envelope.mail_from)
rcpt_tos = [sanitize_email(rcpt_to) for rcpt_to in envelope.rcpt_tos]
envelope.mail_from = mail_from
envelope.rcpt_tos = rcpt_tos
# some emails don't have this header, set the default value (7bit) in this case
if headers.CONTENT_TRANSFER_ENCODING not in msg:
LOG.i("Set CONTENT_TRANSFER_ENCODING")
msg[headers.CONTENT_TRANSFER_ENCODING] = "7bit"
postfix_queue_id = get_queue_id(msg)
if postfix_queue_id:
set_message_id(postfix_queue_id)
else:
LOG.d(
"Cannot parse Postfix queue ID from %s %s",
msg.get_all(headers.RECEIVED),
msg[headers.RECEIVED],
)
if should_ignore(mail_from, rcpt_tos):
LOG.w("Ignore email mail_from=%s rcpt_to=%s", mail_from, rcpt_tos)
return status.E204
# sanitize email headers
sanitize_header(msg, "from")
sanitize_header(msg, "to")
sanitize_header(msg, "cc")
sanitize_header(msg, "reply-to")
LOG.d(
"==>> Handle mail_from:%s, rcpt_tos:%s, header_from:%s, header_to:%s, "
"cc:%s, reply-to:%s, message_id:%s, client_ip:%s, headers:%s, mail_options:%s, rcpt_options:%s",
mail_from,
rcpt_tos,
msg[headers.FROM],
msg[headers.TO],
msg[headers.CC],
msg[headers.REPLY_TO],
msg[headers.MESSAGE_ID],
msg[headers.SL_CLIENT_IP],
msg._headers,
envelope.mail_options,
envelope.rcpt_options,
)
# region mail_from or from_header is a reverse alias which should never happen
email_sent_from_reverse_alias = False
contact = Contact.get_by(reply_email=mail_from)
if contact:
email_sent_from_reverse_alias = True
from_header = get_header_unicode(msg[headers.FROM])
if from_header:
try:
_, from_header_address = parse_full_address(from_header)
except ValueError:
LOG.w("cannot parse the From header %s", from_header)
else:
contact = Contact.get_by(reply_email=from_header_address)
if contact:
email_sent_from_reverse_alias = True
if email_sent_from_reverse_alias:
LOG.w(f"email sent from reverse alias {contact} {contact.alias} {contact.user}")
user = contact.user
send_email_at_most_times(
user,
ALERT_FROM_ADDRESS_IS_REVERSE_ALIAS,
user.email,
"SimpleLogin shouldn't be used with another email forwarding system",
render(
"transactional/email-sent-from-reverse-alias.txt.jinja2",
),
)
# endregion
# unsubscribe request
if UNSUBSCRIBER and (rcpt_tos == [UNSUBSCRIBER] or rcpt_tos == [OLD_UNSUBSCRIBER]):
LOG.d("Handle unsubscribe request from %s", mail_from)
return UnsubscribeHandler().handle_unsubscribe_from_message(envelope, msg)
# region mail sent to VERP
verp_info = get_verp_info_from_email(rcpt_tos[0])
# sent to transactional VERP. Either bounce emails or out-of-office
if (
len(rcpt_tos) == 1
and rcpt_tos[0].startswith(TRANSACTIONAL_BOUNCE_PREFIX)
and rcpt_tos[0].endswith(TRANSACTIONAL_BOUNCE_SUFFIX)
) or (verp_info and verp_info[0] == VerpType.transactional):
if is_bounce(envelope, msg):
handle_transactional_bounce(
envelope, msg, rcpt_tos[0], verp_info and verp_info[1]
)
return status.E205
elif is_automatic_out_of_office(msg):
LOG.d(
"Ignore out-of-office for transactional emails. Headers: %s", msg.items
)
return status.E206
else:
raise VERPTransactional
# sent to forward VERP, can be either bounce or out-of-office
if (
len(rcpt_tos) == 1
and rcpt_tos[0].startswith(BOUNCE_PREFIX)
and rcpt_tos[0].endswith(BOUNCE_SUFFIX)
) or (verp_info and verp_info[0] == VerpType.bounce_forward):
email_log_id = (verp_info and verp_info[1]) or parse_id_from_bounce(rcpt_tos[0])
email_log = EmailLog.get(email_log_id)
if not email_log:
LOG.w("No such email log")
return status.E512
if is_bounce(envelope, msg):
return handle_bounce(envelope, email_log, msg)
elif is_automatic_out_of_office(msg):
handle_out_of_office_forward_phase(email_log, envelope, msg, rcpt_tos)
else:
raise VERPForward
# sent to reply VERP, can be either bounce or out-of-office
if (
len(rcpt_tos) == 1
and rcpt_tos[0].startswith(f"{BOUNCE_PREFIX_FOR_REPLY_PHASE}+")
or (verp_info and verp_info[0] == VerpType.bounce_reply)
):
email_log_id = (verp_info and verp_info[1]) or parse_id_from_bounce(rcpt_tos[0])
email_log = EmailLog.get(email_log_id)
if not email_log:
LOG.w("No such email log")
return status.E512
# bounce by contact
if is_bounce(envelope, msg):
return handle_bounce(envelope, email_log, msg)
elif is_automatic_out_of_office(msg):
handle_out_of_office_reply_phase(email_log, envelope, msg, rcpt_tos)
else:
raise VERPReply(
f"cannot handle email sent to reply VERP, "
f"{email_log.alias} -> {email_log.contact} ({email_log}, {email_log.user}"
)
# iCloud returns the bounce with mail_from=bounce+{email_log_id}+@simplelogin.co, rcpt_to=alias
verp_info = get_verp_info_from_email(mail_from[0])
if (
len(rcpt_tos) == 1
and mail_from.startswith(BOUNCE_PREFIX)
and mail_from.endswith(BOUNCE_SUFFIX)
) or (verp_info and verp_info[0] == VerpType.bounce_forward):
email_log_id = (verp_info and verp_info[1]) or parse_id_from_bounce(mail_from)
email_log = EmailLog.get(email_log_id)
alias = Alias.get_by(email=rcpt_tos[0])
LOG.w(
"iCloud bounces %s %s, saved to%s",
email_log,
alias,
save_email_for_debugging(msg, file_name_prefix="icloud_bounce_"),
)
return handle_bounce(envelope, email_log, msg)
# endregion
# region hotmail, yahoo complaints
if (
len(rcpt_tos) == 1
and mail_from == "staff@hotmail.com"
and rcpt_tos[0] == POSTMASTER
):
LOG.w("Handle hotmail complaint")
# if the complaint cannot be handled, forward it normally
if handle_hotmail_complaint(msg):
return status.E208
if (
len(rcpt_tos) == 1
and mail_from == "feedback@arf.mail.yahoo.com"
and rcpt_tos[0] == POSTMASTER
):
LOG.w("Handle yahoo complaint")
# if the complaint cannot be handled, forward it normally
if handle_yahoo_complaint(msg):
return status.E210
# endregion
if rate_limited(mail_from, rcpt_tos):
LOG.w("Rate Limiting applied for mail_from:%s rcpt_tos:%s", mail_from, rcpt_tos)
# add more logging info. TODO: remove
if len(rcpt_tos) == 1:
alias = Alias.get_by(email=rcpt_tos[0])
if alias:
LOG.w(
"total number email log on %s, %s is %s, %s",
alias,
alias.user,
EmailLog.filter(EmailLog.alias_id == alias.id).count(),
EmailLog.filter(EmailLog.user_id == alias.user_id).count(),
)
if should_ignore_bounce(envelope.mail_from):
return status.E207
else:
return status.E522
# Handle "out-of-office" auto notice, i.e. an automatic response is sent for every forwarded email
if len(rcpt_tos) == 1 and is_reverse_alias(rcpt_tos[0]) and mail_from == "<>":
contact = Contact.get_by(reply_email=rcpt_tos[0])
LOG.w(
"out-of-office email to reverse alias %s. Saved to %s",
contact,
save_email_for_debugging(msg), # todo: remove
)
return status.E206
# result of all deliveries
# each element is a couple of whether the delivery is successful and the smtp status
res: [(bool, str)] = []
nb_rcpt_tos = len(rcpt_tos)
for rcpt_index, rcpt_to in enumerate(rcpt_tos):
if rcpt_to in config.NOREPLIES:
LOG.i("email sent to {} address from {}".format(NOREPLY, mail_from))
send_no_reply_response(mail_from, msg)
return status.E200
# create a copy of msg for each recipient except the last one
# as copy() is a slow function
if rcpt_index < nb_rcpt_tos - 1:
LOG.d("copy message for rcpt %s", rcpt_to)
copy_msg = copy(msg)
else:
copy_msg = msg
# Reply case: the recipient is a reverse alias. Used to start with "reply+" or "ra+"
if is_reverse_alias(rcpt_to):
LOG.d(
"Reply phase %s(%s) -> %s", mail_from, copy_msg[headers.FROM], rcpt_to
)
is_delivered, smtp_status = handle_reply(envelope, copy_msg, rcpt_to)
res.append((is_delivered, smtp_status))
else: # Forward case
LOG.d(
"Forward phase %s(%s) -> %s",
mail_from,
copy_msg[headers.FROM],
rcpt_to,
)
for is_delivered, smtp_status in handle_forward(
envelope, copy_msg, rcpt_to
):
res.append((is_delivered, smtp_status))
# to know whether both successful and unsuccessful deliveries can happen at the same time
nb_success = len([is_success for (is_success, smtp_status) in res if is_success])
# ignore E518 which is a normal condition
nb_non_success = len(
[
is_success
for (is_success, smtp_status) in res
if not is_success and smtp_status != status.E518
]
)
if nb_success > 0 and nb_non_success > 0:
LOG.e(f"some deliveries fail and some success, {mail_from}, {rcpt_tos}, {res}")
for (is_success, smtp_status) in res:
# Consider all deliveries successful if 1 delivery is successful
if is_success:
return smtp_status
# Failed delivery for all, return the first failure
return res[0][1]
def handle_out_of_office_reply_phase(email_log, envelope, msg, rcpt_tos):
"""convert the email into a normal email sent to the alias, so it can be forwarded to mailbox"""
LOG.d(
"send the out-of-office email to the alias %s, old to_header:%s rcpt_tos:%s, %s",
email_log.alias,
msg[headers.TO],
rcpt_tos,
email_log,
)
alias_address = email_log.alias.email
rcpt_tos[0] = alias_address
envelope.rcpt_tos = [alias_address]
add_or_replace_header(msg, headers.TO, alias_address)
# delete reply-to header that can affect email delivery
delete_header(msg, headers.REPLY_TO)
LOG.d(
"after out-of-office transformation to_header:%s reply_to:%s rcpt_tos:%s",
msg.get_all(headers.TO),
msg.get_all(headers.REPLY_TO),
rcpt_tos,
)
def handle_out_of_office_forward_phase(email_log, envelope, msg, rcpt_tos):
"""convert the email into a normal email sent to the reverse alias, so it can be forwarded to contact"""
LOG.d(
"send the out-of-office email to the contact %s, old to_header:%s rcpt_tos:%s %s",
email_log.contact,
msg[headers.TO],
rcpt_tos,
email_log,
)
reverse_alias = email_log.contact.reply_email
rcpt_tos[0] = reverse_alias
envelope.rcpt_tos = [reverse_alias]
add_or_replace_header(msg, headers.TO, reverse_alias)
# delete reply-to header that can affect email delivery
delete_header(msg, headers.REPLY_TO)
LOG.d(
"after out-of-office transformation to_header:%s reply_to:%s rcpt_tos:%s",
msg.get_all(headers.TO),
msg.get_all(headers.REPLY_TO),
rcpt_tos,
)
class MailHandler:
async def handle_DATA(self, server, session, envelope: Envelope):
msg = email.message_from_bytes(envelope.original_content)
try:
ret = self._handle(envelope, msg)
return ret
# happen if reverse-alias is used during the forward phase
# as in this case, a new reverse-alias needs to be created for this reverse-alias -> chaos
except CannotCreateContactForReverseAlias as e:
LOG.w(
"Probably due to reverse-alias used in the forward phase, "
"error:%s mail_from:%s, rcpt_tos:%s, header_from:%s, header_to:%s",
e,
envelope.mail_from,
envelope.rcpt_tos,
msg[headers.FROM],
msg[headers.TO],
)
return status.E524
except (VERPReply, VERPForward, VERPTransactional) as e:
LOG.w(
"email handling fail with error:%s "
"mail_from:%s, rcpt_tos:%s, header_from:%s, header_to:%s",
e,
envelope.mail_from,
envelope.rcpt_tos,
msg[headers.FROM],
msg[headers.TO],
)
return status.E213
except Exception as e:
LOG.e(
"email handling fail with error:%s "
"mail_from:%s, rcpt_tos:%s, header_from:%s, header_to:%s, saved to %s",
e,
envelope.mail_from,
envelope.rcpt_tos,
msg[headers.FROM],
msg[headers.TO],
save_envelope_for_debugging(
envelope, file_name_prefix=e.__class__.__name__
), # todo: remove
)
return status.E404
@newrelic.agent.background_task()
def _handle(self, envelope: Envelope, msg: Message):
start = time.time()
# generate a different message_id to keep track of an email lifecycle
message_id = str(uuid.uuid4())
set_message_id(message_id)
LOG.d("====>=====>====>====>====>====>====>====>")
LOG.i(
"New message, mail from %s, rctp tos %s ",
envelope.mail_from,
envelope.rcpt_tos,
)
newrelic.agent.record_custom_metric(
"Custom/nb_rcpt_tos", len(envelope.rcpt_tos)
)
with create_light_app().app_context():
return_status = handle(envelope, msg)
elapsed = time.time() - start
# Only bounce messages if the return-path passes the spf check. Otherwise black-hole it.
spamd_result = SpamdResult.extract_from_headers(msg)
if return_status[0] == "5":
if spamd_result and spamd_result.spf in (
SPFCheckResult.fail,
SPFCheckResult.soft_fail,
):
LOG.i(
"Replacing 5XX to 216 status because the return-path failed the spf check"
)
return_status = status.E216
LOG.i(
"Finish mail_from %s, rcpt_tos %s, takes %s seconds with return code '%s'<<===",
envelope.mail_from,
envelope.rcpt_tos,
elapsed,
return_status,
)
SpamdResult.send_to_new_relic(msg)
newrelic.agent.record_custom_metric("Custom/email_handler_time", elapsed)
newrelic.agent.record_custom_metric("Custom/number_incoming_email", 1)
return return_status
def main(port: int):
"""Use aiosmtpd Controller"""
controller = Controller(MailHandler(), hostname="0.0.0.0", port=port)
controller.start()
LOG.d("Start mail controller %s %s", controller.hostname, controller.port)
if LOAD_PGP_EMAIL_HANDLER:
LOG.w("LOAD PGP keys")
load_pgp_public_keys()
while True:
time.sleep(2)
if __name__ == "__main__":
parser = argparse.ArgumentParser()
parser.add_argument(
"-p", "--port", help="SMTP port to listen for", type=int, default=20381
)
args = parser.parse_args()
LOG.i("Listen for port %s", args.port)
main(port=args.port)
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