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app-MAIL-temp/email_handler.py
Adrià Casajús e62022f032
Merge remote-tracking branch 'origin/master' into ac-store-contact-bounces 
* origin/master: (29 commits)
  PR comments
  support "enabled" param in /api/v2/aliases
  Update PGPy to 0.5.4 to allow for python 3.10
  Also install libpq-dev
  Fix python 3.10
  Add methods to check if alias will be auto-created
  PR comments
  Allow sending messages in a background thread
  Use the proper import for newrelic agent
  not send emails to inform about an alias can't be created to disabled user
  prevent disabled user from using the api
  make sure disabled user can't create new alias
  Put version version between " so it is 3.10 instead of 3.1
  Add workflow for python 3.10
  Remove it for all creds
  Do not send the transports to the js part since we have not stored them previously
  move help to menu on small screen
  only show the help button on desktop
  use another logo for mobile
  add new parameter disabled in /GET /api/v2/aliases
  ...
2022-04-29 15:56:09 +02:00

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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 formataddr, 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 sqlalchemy.orm.exc import ObjectDeletedError
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,
)
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.spamd_result import (
SpamdResult,
SPFCheckResult,
)
from app.handler.provider_complaint import (
handle_hotmail_complaint,
handle_yahoo_complaint,
)
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
from app.utils import sanitize_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, msg: Message
) -> 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 = "", ""
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(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, use pgpy")
encrypted = pgp_utils.encrypt_file_with_pgpy(msg_bytes, public_key)
second.set_payload(str(encrypted))
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)
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)
try:
contact = get_or_create_contact(from_header, envelope.mail_from, alias, msg)
except ObjectDeletedError:
LOG.d("maybe alias was deleted in the meantime")
alias = Alias.get_by(email=alias_address)
if not alias:
LOG.i("Alias %s was deleted in the meantime", alias_address)
if should_ignore_bounce(envelope.mail_from):
return [(True, status.E207)]
else:
return [(False, status.E515)]
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,
)
res_status = status.E200
if user.block_behaviour == BlockBehaviourEnum.return_5xx:
res_status = status.E502
# do not return 5** to allow user to receive emails later when alias is enabled or contact is unblocked
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:
# 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)
msg = add_header(
msg,
f"""Forwarded by SimpleLogin to {alias.email} with "{orig_subject}" as subject""",
f"""Forwarded by SimpleLogin to {alias.email} 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.e(
"Cannot encrypt message %s -> %s. %s %s", contact, alias, mailbox, user
)
EmailLog.delete(email_log.id, commit=True)
# so the client can retry later
return False, status.E406
# 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
if user.one_click_unsubscribe_block_sender:
unsubscribe_link, via_email = alias.unsubscribe_link(contact)
else:
unsubscribe_link, via_email = alias.unsubscribe_link()
add_or_replace_header(msg, headers.LIST_UNSUBSCRIBE, f"<{unsubscribe_link}>")
if not via_email:
add_or_replace_header(
msg, headers.LIST_UNSUBSCRIBE_POST, "List-Unsubscribe=One-Click"
)
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 = 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,
)
# 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)
# 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 = 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 = 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:
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,
)
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 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 = 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
"""
for mailbox in alias.mailboxes:
if mailbox.email == mail_from:
return mailbox
for authorized_address in mailbox.authorized_addresses:
if authorized_address.email == mail_from:
LOG.d(
"Found an authorized address for %s %s %s",
alias,
mailbox,
authorized_address,
)
return mailbox
return None
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_unsubscribe(envelope: Envelope, msg: Message) -> str:
"""return the SMTP status"""
# format: alias_id:
subject = msg[headers.SUBJECT]
alias, contact = None, None
try:
# subject has the format {alias.id}=
if subject.endswith("="):
alias_id = int(subject[:-1])
alias = Alias.get(alias_id)
# {contact.id}_
elif subject.endswith("_"):
contact_id = int(subject[:-1])
contact = Contact.get(contact_id)
if contact:
alias = contact.alias
# {user.id}*
elif subject.endswith("*"):
user_id = int(subject[:-1])
return handle_unsubscribe_user(user_id, envelope.mail_from)
# some email providers might strip off the = suffix
else:
alias_id = int(subject)
alias = Alias.get(alias_id)
except Exception:
LOG.w("Wrong format subject %s", msg[headers.SUBJECT])
return status.E507
if not alias:
LOG.w("Cannot get alias from subject %s", subject)
return status.E508
mail_from = envelope.mail_from
# Only alias's owning mailbox can send the unsubscribe request
mailbox = get_mailbox_from_mail_from(mail_from, alias)
if not mailbox:
LOG.d(
"%s cannot disable alias %s. Alias authorized addresses:%s",
envelope.mail_from,
alias,
alias.authorized_addresses,
)
return status.E509
user = alias.user
if contact:
contact.block_forward = True
Session.commit()
unblock_contact_url = (
URL
+ f"/dashboard/alias_contact_manager/{alias.id}?highlight_contact_id={contact.id}"
)
for mailbox in alias.mailboxes:
send_email(
mailbox.email,
f"Emails from {contact.website_email} to {alias.email} are now blocked",
render(
"transactional/unsubscribe-block-contact.txt.jinja2",
user=user,
alias=alias,
contact=contact,
unblock_contact_url=unblock_contact_url,
),
)
else:
alias.enabled = False
Session.commit()
enable_alias_url = URL + f"/dashboard/?highlight_alias_id={alias.id}"
for mailbox in alias.mailboxes:
send_email(
mailbox.email,
f"Alias {alias.email} has been disabled successfully",
render(
"transactional/unsubscribe-disable-alias.txt",
user=user,
alias=alias.email,
enable_alias_url=enable_alias_url,
),
render(
"transactional/unsubscribe-disable-alias.html",
user=user,
alias=alias.email,
enable_alias_url=enable_alias_url,
),
)
return status.E202
def handle_unsubscribe_user(user_id: int, mail_from: str) -> str:
"""return the SMTP status"""
user = User.get(user_id)
if not user:
LOG.w("No such user %s %s", user_id, mail_from)
return status.E510
if mail_from != user.email:
LOG.w("Unauthorized mail_from %s %s", user, mail_from)
return status.E511
user.notification = False
Session.commit()
send_email(
user.email,
"You have been unsubscribed from SimpleLogin newsletter",
render(
"transactional/unsubscribe-newsletter.txt",
user=user,
),
render(
"transactional/unsubscribe-newsletter.html",
user=user,
),
)
return status.E202
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 handle_unsubscribe(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])
nb_non_success = len(
[is_success for (is_success, smtp_status) in res if not is_success]
)
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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