app-MAIL-temp/email_handler.py

1800 lines
57 KiB
Python
Raw Normal View History

"""
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
2020-08-16 10:22:16 +02:00
import asyncio
import email
2020-06-10 13:57:23 +02:00
import os
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
2020-11-25 14:43:02 +01:00
from smtplib import SMTP, SMTPRecipientsRefused, SMTPServerDisconnected
2020-09-28 17:41:16 +02:00
from typing import List, Tuple, Optional
2020-08-17 11:39:13 +02:00
import aiosmtpd
2020-08-15 16:38:16 +02:00
import aiospamc
import arrow
import spf
from aiosmtpd.controller import Controller
from aiosmtpd.smtp import Envelope
2020-09-03 19:42:52 +02:00
from sqlalchemy.exc import IntegrityError
from app import pgp_utils, s3
from app.alias_utils import try_auto_create
from app.config import (
EMAIL_DOMAIN,
POSTFIX_SERVER,
URL,
POSTFIX_SUBMISSION_TLS,
2020-03-28 23:19:25 +01:00
UNSUBSCRIBER,
LOAD_PGP_EMAIL_HANDLER,
2020-05-07 13:28:04 +02:00
ENFORCE_SPF,
ALERT_REVERSE_ALIAS_UNKNOWN_MAILBOX,
ALERT_BOUNCE_EMAIL,
ALERT_SPAM_EMAIL,
2020-05-09 23:00:30 +02:00
ALERT_SPF,
POSTFIX_PORT,
2020-06-10 13:57:23 +02:00
SENDER,
SENDER_DIR,
2020-08-15 16:38:16 +02:00
SPAMASSASSIN_HOST,
MAX_SPAM_SCORE,
2020-08-15 16:53:57 +02:00
MAX_REPLY_PHASE_SPAM_SCORE,
ALERT_SEND_EMAIL_CYCLE,
ALERT_MAILBOX_IS_ALIAS,
PGP_SENDER_PRIVATE_KEY,
2020-11-04 12:32:15 +01:00
ALERT_BOUNCE_EMAIL_REPLY_PHASE,
NOREPLY,
)
from app.email_utils import (
send_email,
add_dkim_signature,
2020-01-07 19:50:36 +01:00
add_or_replace_header,
delete_header,
render,
get_orig_message_from_bounce,
2020-03-14 22:24:02 +01:00
delete_all_headers_except,
get_spam_info,
get_orig_message_from_spamassassin_report,
2020-04-05 14:50:12 +02:00
parseaddr_unicode,
send_email_with_rate_control,
2020-06-09 17:16:32 +02:00
get_email_domain_part,
2020-08-21 12:03:23 +02:00
copy,
to_bytes,
get_header_from_bounce,
send_email_at_most_times,
2020-10-15 16:21:31 +02:00
is_valid_alias_address_domain,
should_add_dkim_signature,
add_header,
2020-11-09 21:16:50 +01:00
get_header_unicode,
generate_reply_email,
2020-11-16 19:22:19 +01:00
is_reply_email,
normalize_reply_email,
is_valid_email,
replace,
2020-01-07 19:50:36 +01:00
)
from app.extensions import db
from app.greylisting import greylisting_needed
from app.log import LOG
from app.models import (
Alias,
2020-03-17 10:56:59 +01:00
Contact,
2020-03-17 11:10:50 +01:00
EmailLog,
User,
RefusedEmail,
2020-05-07 13:28:04 +02:00
Mailbox,
)
from app.pgp_utils import PGPException, sign_data_with_pgpy, sign_data
from app.spamassassin_utils import SpamAssassin
2020-11-26 10:38:48 +01:00
from app.utils import random_string
from init_app import load_pgp_public_keys
2020-08-11 16:18:47 +02:00
from server import create_app, create_light_app
# forward or reply
_DIRECTION = "X-SimpleLogin-Type"
_IP_HEADER = "X-SimpleLogin-Client-IP"
_EMAIL_LOG_ID_HEADER = "X-SimpleLogin-EmailLog-ID"
2020-08-25 12:45:55 +02:00
_MESSAGE_ID = "Message-ID"
_ENVELOPE_FROM = "X-SimpleLogin-Envelope-From"
2020-04-13 20:51:29 +02:00
_MIME_HEADERS = [
"MIME-Version",
"Content-Type",
"Content-Disposition",
"Content-Transfer-Encoding",
]
_MIME_HEADERS = [h.lower() for h in _MIME_HEADERS]
# fix the database connection leak issue
# use this method instead of create_app
def new_app():
2020-08-11 16:18:47 +02:00
app = create_light_app()
@app.teardown_appcontext
def shutdown_session(response_or_exc):
# same as shutdown_session() in flask-sqlalchemy but this is not enough
db.session.remove()
# dispose the engine too
db.engine.dispose()
return 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
"""
contact_name, contact_email = parseaddr_unicode(from_header)
if not is_valid_email(contact_email):
# From header is wrongly formatted, try with mail_from
if mail_from and mail_from != "<>":
2020-11-25 15:20:00 +01:00
LOG.warning(
"Cannot parse email from from_header %s, parse from mail_from %s",
from_header,
2020-11-25 15:20:00 +01:00
mail_from,
)
_, contact_email = parseaddr_unicode(mail_from)
if not is_valid_email(contact_email):
LOG.warning(
"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 = ""
2020-04-04 20:06:35 +02:00
contact = Contact.get_by(alias_id=alias.id, website_email=contact_email)
2020-03-17 10:56:59 +01:00
if contact:
if contact.name != contact_name:
LOG.d(
2020-08-27 10:20:48 +02:00
"Update contact %s name %s to %s",
contact,
contact.name,
contact_name,
)
contact.name = contact_name
db.session.commit()
2020-11-25 15:20:00 +01:00
# contact created in the past does not have mail_from and from_header field
if not contact.mail_from and mail_from:
LOG.d(
2020-11-25 15:20:00 +01:00
"Set contact mail_from %s: %s to %s",
contact,
contact.mail_from,
mail_from,
)
contact.mail_from = mail_from
db.session.commit()
if not contact.from_header and from_header:
LOG.d(
2020-11-25 15:20:00 +01:00
"Set contact from_header %s: %s to %s",
contact,
contact.from_header,
from_header,
)
contact.from_header = from_header
db.session.commit()
else:
2020-11-25 15:20:00 +01:00
LOG.d(
"create contact %s for alias %s",
contact_email,
2020-08-27 10:20:48 +02:00
alias,
)
2020-09-03 19:42:52 +02:00
try:
contact = Contact.create(
user_id=alias.user_id,
alias_id=alias.id,
website_email=contact_email,
name=contact_name,
mail_from=mail_from,
from_header=from_header,
2020-11-18 11:48:09 +01:00
reply_email=generate_reply_email(contact_email)
if is_valid_email(contact_email)
2020-11-18 11:48:09 +01:00
else NOREPLY,
2020-09-03 19:42:52 +02:00
)
2020-11-18 11:48:09 +01:00
if not contact_email:
LOG.d("Create a contact with invalid email for %s", alias)
contact.invalid_email = True
2020-09-03 19:42:52 +02:00
db.session.commit()
except IntegrityError:
LOG.warning("Contact %s %s already exist", alias, contact_email)
db.session.rollback()
contact = Contact.get_by(alias_id=alias.id, website_email=contact_email)
2020-03-17 10:56:59 +01:00
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, [])
for contact_name, contact_email in getaddresses(headers):
# convert back to original then parse again to make sure contact_name is unicode
addr = formataddr((contact_name, contact_email))
contact_name, contact = parseaddr_unicode(addr)
# no transformation when alias is already in the header
2020-04-05 12:59:36 +02:00
if contact_email == alias.email:
new_addrs.append(addr)
continue
if not is_valid_email(contact_email):
2020-11-30 10:50:16 +01:00
LOG.warning("invalid contact email %s. %s. Skip", contact_email, headers)
continue
2020-04-05 12:59:36 +02:00
contact = Contact.get_by(alias_id=alias.id, website_email=contact_email)
if contact:
2020-04-05 15:39:48 +02:00
# update the contact name if needed
2020-04-05 14:50:12 +02:00
if contact.name != contact_name:
LOG.d(
"Update contact %s name %s to %s",
contact,
contact.name,
contact_name,
)
contact.name = contact_name
db.session.commit()
else:
LOG.debug(
"create contact for alias %s and email %s, header %s",
alias,
2020-04-05 12:59:36 +02:00
contact_email,
header,
)
try:
contact = Contact.create(
user_id=alias.user_id,
alias_id=alias.id,
website_email=contact_email,
name=contact_name,
reply_email=generate_reply_email(contact_email),
is_cc=header.lower() == "cc",
from_header=addr,
)
db.session.commit()
except IntegrityError:
LOG.warning("Contact %s %s already exist", alias, contact_email)
db.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 replace_header_when_reply(msg: Message, alias: Alias, header: str):
"""
Replace CC or To Reply emails by original emails
"""
new_addrs: [str] = []
for _, reply_email in getaddresses(msg.get_all(header, [])):
# no transformation when alias is already in the header
if reply_email == alias.email:
continue
contact = Contact.get_by(reply_email=reply_email)
if not contact:
LOG.warning(
"%s email in reply phase %s must be reply emails", header, 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)
2020-03-17 12:10:13 +01:00
def should_append_alias(msg: Message, address: str):
"""whether an alias should be appended to TO header in message"""
# # force convert header to string, sometimes addrs is Header object
if msg["To"] and address.lower() in str(msg["To"]).lower():
return False
if msg["Cc"] and address.lower() in str(msg["Cc"]).lower():
return False
return True
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 _MIME_HEADERS:
msg[header_name] = clone_msg._headers[i][1]
# Delete unnecessary headers in clone_msg except _MIME_HEADERS to save space
2020-03-14 22:24:02 +01:00
delete_all_headers_except(
clone_msg,
2020-08-27 10:20:48 +02:00
_MIME_HEADERS,
2020-03-14 22:24:02 +01:00
)
if clone_msg["Content-Type"] is None:
LOG.d("Content-Type missing")
clone_msg["Content-Type"] = "text/plain"
if clone_msg["Mime-Version"] is None:
LOG.d("Mime-Version missing")
clone_msg["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
2020-10-28 17:07:53 +01:00
# use pgpy as fallback
2020-11-09 17:02:10 +01:00
msg_bytes = to_bytes(clone_msg)
2020-10-28 17:07:53 +01:00
try:
encrypted_data = pgp_utils.encrypt_file(BytesIO(msg_bytes), pgp_fingerprint)
2020-10-28 17:07:53 +01:00
second.set_payload(encrypted_data)
except PGPException:
LOG.warning("Cannot encrypt using python-gnupg, use pgpy")
encrypted = pgp_utils.encrypt_file_with_pgpy(msg_bytes, public_key)
2020-10-28 17:07:53 +01:00
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:
2020-11-09 17:02:10 +01:00
signature.set_payload(sign_data(to_bytes(msg).replace(b"\n", b"\r\n")))
except Exception:
LOG.exception("Cannot sign, try using pgpy")
signature.set_payload(
2020-11-09 17:02:10 +01:00
sign_data_with_pgpy(to_bytes(msg).replace(b"\n", b"\r\n"))
)
container.attach(signature)
return container
def handle_email_sent_to_ourself(alias, mailbox, msg: Message, user):
# store the refused email
random_name = str(uuid.uuid4())
full_report_path = f"refused-emails/cycle-{random_name}.eml"
2020-11-09 17:02:10 +01:00
s3.upload_email_from_bytesio(full_report_path, BytesIO(to_bytes(msg)), random_name)
refused_email = RefusedEmail.create(
path=None, full_report_path=full_report_path, user_id=alias.user_id
)
db.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,
mailbox.email,
2020-08-27 11:10:16 +02:00
f"Email sent to {alias.email} from its own mailbox {mailbox.email}",
render(
"transactional/cycle-email.txt",
name=user.name or "",
alias=alias,
mailbox=mailbox,
refused_email_url=refused_email_url,
),
render(
"transactional/cycle-email.html",
name=user.name or "",
alias=alias,
mailbox=mailbox,
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)
2020-03-28 21:24:43 +01:00
"""
address = rcpt_to # alias@SL
2020-03-19 11:15:02 +01:00
alias = Alias.get_by(email=address)
if not alias:
LOG.d("alias %s not exist. Try to see if it can be created on the fly", address)
2020-03-19 11:15:02 +01:00
alias = try_auto_create(address)
if not alias:
LOG.d("alias %s cannot be created on-the-fly, return 550", address)
2020-07-05 16:25:54 +02:00
return [(False, "550 SL E3 Email not exist")]
2020-11-04 12:32:15 +01:00
user = alias.user
if user.disabled:
LOG.warning("User %s disabled, disable forwarding emails for %s", user, alias)
return [(False, "550 SL E20 Account disabled")]
mail_from = envelope.mail_from
for mb in alias.mailboxes:
# email send from a mailbox to alias
if mb.email == mail_from:
LOG.warning("cycle email sent from %s to %s", mb, alias)
2020-11-04 12:32:15 +01:00
handle_email_sent_to_ourself(alias, mb, msg, user)
return [(True, "250 Message accepted for delivery")]
# bounce email initiated by Postfix
# can happen in case an email cannot be sent from an alias to a contact
# in this case Postfix will send a bounce report to original sender, which is the alias
2020-11-05 10:26:19 +01:00
# if mail_from == "<>":
# LOG.warning("Bounce email sent to %s", alias)
#
# handle_bounce_reply_phase(alias, msg, user)
# return [(False, "550 SL E24 Email cannot be sent to contact")]
LOG.d("Create or get contact for %s %s", msg["From"], msg["Reply-To"])
# prefer using Reply-To when creating contact
if msg["Reply-To"]:
# force convert header to string, sometimes contact_from_header is Header object
LOG.d("Use Reply-To header")
from_header = str(msg["Reply-To"])
else:
from_header = str(msg["From"])
contact = get_or_create_contact(from_header, envelope.mail_from, alias)
2020-11-04 12:32:15 +01:00
if not alias.enabled:
LOG.d("%s is disabled, do not forward", alias)
EmailLog.create(
contact_id=contact.id, user_id=contact.user_id, blocked=True, commit=True
)
db.session.commit()
# do not return 5** to allow user to receive emails later when alias is enabled
return [(True, "250 Message accepted for delivery")]
ret = []
mailboxes = alias.mailboxes
# no valid mailbox
if not mailboxes:
return [(False, "550 SL E16 invalid mailbox")]
# no need to create a copy of message
2020-11-04 14:55:54 +01:00
for mailbox in mailboxes:
2020-09-10 09:38:30 +02:00
if not mailbox.verified:
LOG.debug("Mailbox %s unverified, do not forward", mailbox)
2020-11-04 14:55:54 +01:00
ret.append((False, "550 SL E19 unverified mailbox"))
2020-09-10 09:38:30 +02:00
else:
2020-11-04 14:55:54 +01:00
# create a copy of message for each forward
2020-09-10 09:38:30 +02:00
ret.append(
forward_email_to_mailbox(
2020-11-04 14:55:54 +01:00
alias,
copy(msg),
contact,
envelope,
mailbox,
user,
2020-09-10 09:38:30 +02:00
)
)
return ret
def forward_email_to_mailbox(
alias,
msg: Message,
contact: Contact,
envelope,
mailbox,
user,
) -> (bool, str):
LOG.d("Forward %s -> %s -> %s", contact, alias, mailbox)
2020-06-09 17:16:32 +02:00
if mailbox.disabled:
LOG.debug("%s disabled, do not forward")
return False, "550 SL E21 Disabled mailbox"
2020-06-09 17:16:32 +02:00
# sanity check: make sure mailbox is not actually an alias
if get_email_domain_part(alias.email) == get_email_domain_part(mailbox.email):
LOG.exception(
2020-06-09 17:16:32 +02:00
"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 SimpleLogin mailbox {mailbox.email} cannot be an email alias",
render(
"transactional/mailbox-invalid.txt",
name=user.name or "",
mailbox=mailbox,
mailbox_url=mailbox_url,
),
render(
"transactional/mailbox-invalid.html",
name=user.name or "",
mailbox=mailbox,
mailbox_url=mailbox_url,
),
max_nb_alert=1,
)
2020-08-30 19:08:53 +02:00
# retry later
# so when user fixes the mailbox, the email can be delivered
return False, "421 SL E14"
2020-06-09 17:16:32 +02:00
email_log = EmailLog.create(
2020-11-24 17:02:09 +01:00
contact_id=contact.id, user_id=user.id, mailbox_id=mailbox.id, commit=True
)
2020-08-15 16:53:57 +02:00
# Spam check
2020-08-15 16:38:16 +02:00
spam_status = ""
is_spam = False
if SPAMASSASSIN_HOST:
start = time.time()
spam_score = get_spam_score(msg)
LOG.d(
"%s -> %s - spam score %s in %s seconds",
contact,
alias,
spam_score,
time.time() - start,
)
2020-08-16 14:28:47 +02:00
email_log.spam_score = spam_score
2020-08-20 11:58:46 +02:00
db.session.commit()
2020-08-15 16:38:16 +02:00
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
spam_status = "Spam detected by SpamAssassin server"
else:
is_spam, spam_status = get_spam_info(msg, max_score=user.max_spam_score)
if is_spam:
LOG.warning("Email detected as spam. Alias: %s, from: %s", alias, contact)
email_log.is_spam = True
email_log.spam_status = spam_status
2020-08-20 11:58:46 +02:00
db.session.commit()
2020-08-21 10:18:58 +02:00
handle_spam(contact, alias, msg, user, mailbox, email_log)
2020-07-05 16:25:54 +02:00
return False, "550 SL E1 Email detected as spam"
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""",
)
# create PGP email if needed
2020-11-24 11:28:14 +01:00
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)
2020-11-07 17:23:28 +01:00
orig_subject = msg["Subject"]
2020-11-09 21:16:50 +01:00
orig_subject = get_header_unicode(orig_subject)
add_or_replace_header(msg, "Subject", mailbox.generic_subject)
msg = add_header(
msg,
2020-11-07 17:23:28 +01:00
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""",
)
2020-06-08 13:54:42 +02:00
try:
msg = prepare_pgp_message(
msg, mailbox.pgp_finger_print, mailbox.pgp_public_key, can_sign=True
)
2020-06-08 13:54:42 +02:00
except PGPException:
LOG.exception(
2020-06-08 13:54:42 +02:00
"Cannot encrypt message %s -> %s. %s %s", contact, alias, mailbox, user
)
# so the client can retry later
2020-07-05 16:25:54 +02:00
return False, "421 SL E12 Retry later"
# add custom header
add_or_replace_header(msg, _DIRECTION, "Forward")
# remove reply-to & sender header if present
delete_header(msg, "Reply-To")
delete_header(msg, "Sender")
delete_header(msg, _IP_HEADER)
add_or_replace_header(msg, _EMAIL_LOG_ID_HEADER, str(email_log.id))
2020-08-25 12:45:55 +02:00
add_or_replace_header(msg, _MESSAGE_ID, make_msgid(str(email_log.id), EMAIL_DOMAIN))
add_or_replace_header(msg, _ENVELOPE_FROM, envelope.mail_from)
if not msg["Date"]:
date_header = formatdate()
msg["Date"] = date_header
2020-11-01 18:13:50 +01:00
# change the from header so the sender comes from a reverse-alias
# so it can pass DMARC check
# replace the email part in from: header
contact_from_header = msg["From"]
new_from_header = contact.new_addr()
add_or_replace_header(msg, "From", new_from_header)
LOG.d("new_from_header:%s, old header %s", new_from_header, contact_from_header)
2020-11-01 18:13:50 +01:00
# replace CC & To emails by reverse-alias for all emails that are not alias
replace_header_when_forward(msg, alias, "Cc")
replace_header_when_forward(msg, alias, "To")
# append alias into the TO header if it's not present in To or CC
if should_append_alias(msg, alias.email):
LOG.d("append alias %s to TO header %s", alias, msg["To"])
if msg["To"]:
to_header = msg["To"] + "," + alias.email
2020-03-28 23:19:25 +01:00
else:
to_header = alias.email
add_or_replace_header(msg, "To", to_header.strip())
# add List-Unsubscribe header
unsubscribe_link, via_email = alias.unsubscribe_link()
add_or_replace_header(msg, "List-Unsubscribe", f"<{unsubscribe_link}>")
if not via_email:
add_or_replace_header(
msg, "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(
contact.reply_email,
mailbox.email,
msg,
envelope.mail_options,
envelope.rcpt_options,
)
except SMTPRecipientsRefused:
# that means the mailbox is maybe invalid
LOG.warning(
"SMTPRecipientsRefused forward phase %s -> %s -> %s",
contact,
alias,
mailbox,
)
# return 421 so Postfix can retry later
return False, "421 SL E17 Retry later"
else:
db.session.commit()
return True, "250 Message accepted for delivery"
def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
2020-03-28 21:24:43 +01:00
"""
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.warning(f"Reply email {reply_email} has wrong domain")
2020-04-13 19:33:45 +02:00
return False, "550 SL E2"
# handle case where reply email is generated with non-allowed char
reply_email = normalize_reply_email(reply_email)
2020-03-17 10:56:59 +01:00
contact = Contact.get_by(reply_email=reply_email)
if not contact:
LOG.warning(f"No such forward-email with {reply_email} as reply-email")
2020-07-05 16:25:54 +02:00
return False, "550 SL E4 Email not exist"
2019-12-18 17:07:20 +01:00
alias = contact.alias
address: str = contact.alias.email
2020-12-06 13:54:59 +01:00
alias_domain = address[address.find("@") + 1:]
2020-10-15 16:21:31 +02:00
# 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.exception("%s domain isn't known", alias)
return False, "550 SL E5"
user = alias.user
mail_from = envelope.mail_from
if user.disabled:
LOG.exception(
"User %s disabled, disable sending emails from %s to %s",
user,
alias,
contact,
)
return [(False, "550 SL E20 Account disabled")]
# bounce email initiated by Postfix
# can happen in case emails cannot be delivered to user-email
# in this case Postfix will try to send a bounce report to original sender, which is
# the "reply email"
if mail_from == "<>":
LOG.warning(
2020-08-27 10:20:48 +02:00
"Bounce when sending to alias %s from %s, user %s",
alias,
contact,
user,
)
handle_bounce(contact, alias, msg, user)
2020-04-13 19:33:45 +02:00
return False, "550 SL E6"
# 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.warning(
"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 False, "550 SL E7"
if ENFORCE_SPF and mailbox.force_spf and not alias.disable_email_spoofing_check:
2020-05-09 22:54:55 +02:00
ip = msg[_IP_HEADER]
if not spf_pass(ip, envelope, mailbox, user, alias, contact.website_email, msg):
# cannot use 4** here as sender will retry. 5** because that generates bounce report
return True, "250 SL E11"
2020-05-07 13:28:04 +02:00
2020-08-16 14:28:47 +02:00
email_log = EmailLog.create(
contact_id=contact.id,
is_reply=True,
user_id=contact.user_id,
mailbox_id=mailbox.id,
2020-08-16 14:28:47 +02:00
)
2020-08-15 16:53:57 +02:00
# Spam check
spam_status = ""
is_spam = False
# do not use user.max_spam_score here
if SPAMASSASSIN_HOST:
2020-08-24 17:47:56 +02:00
start = time.time()
spam_score = get_spam_score(msg)
2020-08-24 17:47:56 +02:00
LOG.d(
"%s -> %s - spam score %s in %s seconds",
alias,
contact,
spam_score,
time.time() - start,
)
2020-08-16 14:28:47 +02:00
email_log.spam_score = spam_score
2020-08-15 16:53:57 +02:00
if spam_score > MAX_REPLY_PHASE_SPAM_SCORE:
is_spam = True
spam_status = "Spam detected by SpamAssassin server"
else:
is_spam, spam_status = get_spam_info(msg, max_score=MAX_REPLY_PHASE_SPAM_SCORE)
if is_spam:
LOG.exception(
2020-11-09 17:03:47 +01:00
"Reply phase - email sent from %s to %s detected as spam. %s",
alias,
contact,
user,
2020-08-15 16:53:57 +02:00
)
2020-08-16 14:28:47 +02:00
2020-08-15 16:53:57 +02:00
email_log.is_spam = True
email_log.spam_status = spam_status
db.session.commit()
2020-08-21 10:18:58 +02:00
handle_spam(contact, alias, msg, user, mailbox, email_log, is_reply=True)
2020-08-15 16:53:57 +02:00
return False, "550 SL E15 Email detected as spam"
delete_all_headers_except(
msg,
[
"From",
"To",
"Cc",
"Subject",
]
+ _MIME_HEADERS,
)
2020-11-01 18:12:09 +01:00
# replace the reverse-alias (i.e. "ra+string@simplelogin.co") 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.exception(
"Cannot encrypt message %s -> %s. %s %s", alias, contact, mailbox, user
)
# to not save the email_log
db.session.rollback()
# return 421 so the client can retry later
return False, "421 SL E13 Retry later"
2020-11-04 12:32:15 +01:00
# save the email_log to DB
db.session.commit()
# make the email comes from alias
from_header = alias.email
# add alias name from alias
2020-04-26 10:41:24 +02:00
if alias.name:
LOG.d("Put alias name in from header")
from_header = formataddr((alias.name, alias.email))
elif alias.custom_domain:
LOG.d("Put domain default alias name in from header")
# add alias name from domain
if alias.custom_domain.name:
from_header = formataddr((alias.custom_domain.name, alias.email))
2020-04-26 10:41:24 +02:00
add_or_replace_header(msg, "From", from_header)
replace_header_when_reply(msg, alias, "To")
replace_header_when_reply(msg, alias, "Cc")
2020-08-25 12:45:55 +02:00
add_or_replace_header(
msg,
_MESSAGE_ID,
make_msgid(str(email_log.id), get_email_domain_part(alias.email)),
)
date_header = formatdate()
msg["Date"] = date_header
2020-11-04 12:32:15 +01:00
msg[_DIRECTION] = "Reply"
msg[_EMAIL_LOG_ID_HEADER] = str(email_log.id)
LOG.d(
"send email from %s to %s, mail_options:%s,rcpt_options:%s",
alias.email,
2020-03-17 10:56:59 +01:00
contact.website_email,
envelope.mail_options,
envelope.rcpt_options,
)
if should_add_dkim_signature(alias_domain):
add_dkim_signature(msg, alias_domain)
2020-06-20 16:19:01 +02:00
try:
sl_sendmail(
2020-06-20 16:19:01 +02:00
alias.email,
contact.website_email,
msg,
2020-06-20 16:19:01 +02:00
envelope.mail_options,
envelope.rcpt_options,
)
except Exception:
2020-08-16 14:28:47 +02:00
# to not save the email_log
db.session.rollback()
LOG.warning("Cannot send email from %s to %s", alias, contact)
2020-06-20 16:19:01 +02:00
send_email(
mailbox.email,
f"Email cannot be sent to {contact.email} from {alias.email}",
render(
"transactional/reply-error.txt",
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
2020-11-04 12:32:15 +01:00
2020-03-28 21:24:43 +01:00
return True, "250 Message accepted for delivery"
2020-09-28 17:41:16 +02:00
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 address in mailbox.authorized_addresses:
if address.email == mail_from:
LOG.debug(
"Found an authorized address for %s %s %s", alias, mailbox, address
)
return mailbox
return None
def spf_pass(
ip: str,
envelope,
mailbox: Mailbox,
user: User,
alias: Alias,
contact_email: str,
msg: Message,
) -> bool:
if ip:
LOG.d("Enforce SPF")
try:
r = spf.check2(i=ip, s=envelope.mail_from, h=None)
except Exception:
LOG.exception("SPF error, mailbox %s, ip %s", mailbox.email, ip)
else:
# TODO: Handle temperr case (e.g. dns timeout)
# only an absolute pass, or no SPF policy at all is 'valid'
if r[0] not in ["pass", "none"]:
2020-06-06 23:38:19 +02:00
LOG.warning(
"SPF fail for mailbox %s, reason %s, failed IP %s",
mailbox.email,
r[0],
ip,
)
subject = get_header_unicode(msg["Subject"])
send_email_with_rate_control(
user,
ALERT_SPF,
mailbox.email,
f"SimpleLogin Alert: attempt to send emails from your alias {alias.email} from unknown IP Address",
render(
"transactional/spf-fail.txt",
name=user.name,
alias=alias.email,
ip=ip,
mailbox_url=URL + f"/dashboard/mailbox/{mailbox.id}#spf",
to_email=contact_email,
subject=subject,
time=arrow.now(),
),
render(
"transactional/spf-fail.html",
name=user.name,
alias=alias.email,
ip=ip,
mailbox_url=URL + f"/dashboard/mailbox/{mailbox.id}#spf",
to_email=contact_email,
subject=subject,
time=arrow.now(),
),
)
return False
else:
LOG.warning(
"Could not find %s header %s -> %s",
_IP_HEADER,
mailbox.email,
contact_email,
)
return True
def handle_unknown_mailbox(
envelope, msg, reply_email: str, user: User, alias: Alias, contact: Contact
):
LOG.warning(
2020-12-06 13:54:59 +01:00
"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["From"],
reply_email,
alias,
user,
contact,
)
authorize_address_link = (
f"{URL}/dashboard/mailbox/{alias.mailbox_id}/#authorized-address"
)
2020-09-29 13:03:15 +02:00
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",
name=user.name,
alias=alias,
sender=envelope.mail_from,
authorize_address_link=authorize_address_link,
2020-09-29 13:11:04 +02:00
mailbox_emails=mailbox_emails,
),
render(
"transactional/reply-must-use-personal-email.html",
name=user.name,
alias=alias,
sender=envelope.mail_from,
authorize_address_link=authorize_address_link,
2020-09-29 13:11:04 +02:00
mailbox_emails=mailbox_emails,
),
)
# Notify sender that they cannot send emails to this address
send_email_with_rate_control(
user,
ALERT_REVERSE_ALIAS_UNKNOWN_MAILBOX,
envelope.mail_from,
f"Your email ({envelope.mail_from}) is not allowed to send emails to {reply_email}",
render(
"transactional/send-from-alias-from-unknown-sender.txt",
sender=envelope.mail_from,
reply_email=reply_email,
),
render(
"transactional/send-from-alias-from-unknown-sender.html",
sender=envelope.mail_from,
reply_email=reply_email,
),
)
def handle_bounce(contact: Contact, alias: Alias, msg: Message, user: User):
2020-11-24 16:38:54 +01:00
"""
Handle bounce that is sent to the reverse-alias
Happens when an email cannot be to a mailbox
"""
disable_alias_link = f"{URL}/dashboard/unsubscribe/{alias.id}"
# Store the bounced email
2020-03-15 18:39:59 +01:00
# generate a name for the email
random_name = str(uuid.uuid4())
full_report_path = f"refused-emails/full-{random_name}.eml"
2020-11-09 17:02:10 +01:00
s3.upload_email_from_bytesio(full_report_path, BytesIO(to_bytes(msg)), random_name)
file_path = None
2020-11-24 16:50:55 +01:00
2020-05-16 18:24:51 +02:00
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.warning(
2020-05-16 18:24:51 +02:00
"Cannot parse original message from bounce message %s %s %s %s",
alias,
user,
contact,
2020-05-16 18:24:51 +02:00
full_report_path,
2020-03-22 16:56:08 +01:00
)
else:
file_path = f"refused-emails/{random_name}.eml"
2020-11-09 17:02:10 +01:00
s3.upload_email_from_bytesio(file_path, BytesIO(to_bytes(msg)), random_name)
refused_email = RefusedEmail.create(
path=file_path, full_report_path=full_report_path, user_id=user.id
)
db.session.flush()
LOG.d("Create refused email %s", refused_email)
2020-11-24 16:50:55 +01:00
# try to parse email_log
email_log = None
try:
email_log_id = int(get_header_from_bounce(msg, _EMAIL_LOG_ID_HEADER))
except Exception:
LOG.warning("cannot get email log id from bounce report, %s", refused_email)
else:
email_log = EmailLog.get(email_log_id)
2020-11-24 16:50:55 +01:00
# create new email_log if unable to parse from bounce report
if not email_log:
LOG.warning("cannot get the original email_log, create a new one")
email_log: EmailLog = EmailLog.create(
contact_id=contact.id, user_id=contact.user_id
)
2020-08-20 14:28:57 +02:00
2020-11-24 16:50:55 +01:00
# try to get mailbox
mailbox = None
if email_log:
mailbox = email_log.mailbox
# use the default mailbox if unable to parse from bounce report
if not mailbox:
LOG.warning("Use %s default mailbox %s", alias, refused_email)
mailbox = alias.mailbox
email_log.bounced = True
2020-04-04 19:21:31 +02:00
email_log.refused_email_id = refused_email.id
2020-05-10 18:35:13 +02:00
email_log.bounced_mailbox_id = mailbox.id
db.session.commit()
2020-12-06 13:54:59 +01:00
refused_email_url = f"{URL}/dashboard/refused_email?highlight_id={email_log.id}"
2020-08-21 10:32:10 +02:00
nb_bounced = EmailLog.filter_by(contact_id=contact.id, bounced=True).count()
if nb_bounced >= 2 and alias.cannot_be_disabled:
LOG.warning("%s cannot be disabled", alias)
# inform user if this is the first bounced email
if nb_bounced == 1 or (nb_bounced >= 2 and alias.cannot_be_disabled):
LOG.d(
"Inform user %s about bounced email sent by %s to alias %s",
user,
contact.website_email,
2020-08-21 10:32:10 +02:00
alias,
)
send_email_with_rate_control(
user,
ALERT_BOUNCE_EMAIL,
user.email,
2020-08-21 10:32:10 +02:00
f"Email from {contact.website_email} to {alias.email} cannot be delivered to your inbox",
render(
"transactional/bounced-email.txt",
name=user.name,
alias=alias,
2020-03-17 10:56:59 +01:00
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
mailbox_email=mailbox.email,
),
render(
"transactional/bounced-email.html",
name=user.name,
alias=alias,
2020-03-17 10:56:59 +01:00
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
mailbox_email=mailbox.email,
),
)
# disable the alias the second time email is bounced
elif nb_bounced >= 2:
LOG.d(
"Bounce happens again with alias %s from %s. Disable alias now ",
alias,
contact.website_email,
)
alias.enabled = False
db.session.commit()
send_email_with_rate_control(
user,
ALERT_BOUNCE_EMAIL,
user.email,
2020-08-21 10:32:10 +02:00
f"Alias {alias.email} has been disabled due to second undelivered email from {contact.website_email}",
render(
"transactional/automatic-disable-alias.txt",
name=user.name,
alias=alias,
2020-03-17 10:56:59 +01:00
website_email=contact.website_email,
refused_email_url=refused_email_url,
mailbox_email=mailbox.email,
),
render(
"transactional/automatic-disable-alias.html",
name=user.name,
alias=alias,
2020-03-17 10:56:59 +01:00
website_email=contact.website_email,
refused_email_url=refused_email_url,
mailbox_email=mailbox.email,
),
)
2020-11-04 12:32:15 +01:00
def handle_bounce_reply_phase(alias: Alias, msg: Message, user: User):
"""
Handle bounce that is sent to alias
Happens when an email cannot be sent from an alias to a contact
"""
2020-11-04 15:38:26 +01:00
try:
email_log_id = int(get_header_from_bounce(msg, _EMAIL_LOG_ID_HEADER))
except Exception:
# save the data for debugging
file_path = f"/tmp/{random_string(10)}.eml"
with open(file_path, "wb") as f:
2020-11-09 17:02:10 +01:00
f.write(to_bytes(msg))
2020-11-04 15:38:26 +01:00
LOG.exception(
"Cannot get email-log-id from bounced report, %s %s %s",
alias,
user,
file_path,
)
return
email_log = EmailLog.get(email_log_id)
contact = email_log.contact
2020-11-04 12:32:15 +01:00
# 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"
2020-11-09 17:02:10 +01:00
s3.upload_email_from_bytesio(full_report_path, BytesIO(to_bytes(msg)), random_name)
2020-11-04 12:32:15 +01:00
orig_msg = get_orig_message_from_bounce(msg)
2020-11-04 15:38:26 +01:00
file_path = None
if orig_msg:
file_path = f"refused-emails/{random_name}.eml"
s3.upload_email_from_bytesio(
2020-11-09 17:02:10 +01:00
file_path, BytesIO(to_bytes(orig_msg)), random_name
2020-11-04 15:38:26 +01:00
)
2020-11-04 12:32:15 +01:00
2020-11-04 15:38:26 +01:00
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)
2020-11-04 12:32:15 +01:00
2020-11-04 15:38:26 +01:00
email_log.bounced = True
email_log.refused_email_id = refused_email.id
2020-11-04 12:32:15 +01:00
2020-11-24 16:50:55 +01:00
mailbox = email_log.mailbox or alias.mailbox
email_log.bounced_mailbox_id = mailbox.id
db.session.commit()
2020-11-04 12:32:15 +01:00
2020-12-06 13:54:59 +01:00
refused_email_url = f"{URL}/dashboard/refused_email?highlight_id={email_log.id}"
2020-11-04 12:32:15 +01:00
LOG.d(
"Inform user %s about bounced email sent by %s to %s",
user,
alias,
contact,
)
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-email-reply-phase.txt",
alias=alias,
contact=contact,
refused_email_url=refused_email_url,
),
render(
"transactional/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,
2020-08-21 10:18:58 +02:00
mailbox: Mailbox,
email_log: EmailLog,
2020-08-15 16:53:57 +02:00
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())
2020-04-02 18:09:05 +02:00
full_report_path = f"spams/full-{random_name}.eml"
2020-11-09 17:02:10 +01:00
s3.upload_email_from_bytesio(full_report_path, BytesIO(to_bytes(msg)), random_name)
file_path = None
if orig_msg:
2020-04-02 18:09:05 +02:00
file_path = f"spams/{random_name}.eml"
s3.upload_email_from_bytesio(
2020-11-09 17:02:10 +01:00
file_path, BytesIO(to_bytes(orig_msg)), random_name
)
refused_email = RefusedEmail.create(
path=file_path, full_report_path=full_report_path, user_id=user.id
)
db.session.flush()
email_log.refused_email_id = refused_email.id
db.session.commit()
LOG.d("Create spam email %s", refused_email)
2020-12-06 13:54:59 +01:00
refused_email_url = f"{URL}/dashboard/refused_email?highlight_id={email_log.id}"
disable_alias_link = f"{URL}/dashboard/unsubscribe/{alias.id}"
2020-08-15 16:53:57 +02:00
if is_reply:
LOG.d(
2020-12-02 12:40:29 +01:00
"Inform %s (%s) about spam email sent from alias %s to %s. %s",
2020-08-21 10:20:08 +02:00
mailbox,
2020-08-15 16:53:57 +02:00
user,
alias,
contact,
2020-12-02 12:40:29 +01:00
refused_email,
2020-08-15 16:53:57 +02:00
)
send_email_with_rate_control(
user,
ALERT_SPAM_EMAIL,
2020-08-21 10:18:58 +02:00
mailbox.email,
2020-11-18 16:16:37 +01:00
f"Email from {alias.email} to {contact.website_email} is detected as spam",
2020-08-15 16:53:57 +02:00
render(
"transactional/spam-email-reply-phase.txt",
name=user.name,
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",
name=user.name,
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
),
)
else:
# inform user
LOG.d(
2020-08-21 10:20:08 +02:00
"Inform %s (%s) about spam email sent by %s to alias %s",
mailbox,
2020-08-15 16:53:57 +02:00
user,
contact,
alias,
)
send_email_with_rate_control(
user,
ALERT_SPAM_EMAIL,
2020-08-21 10:18:58 +02:00
mailbox.email,
2020-08-15 16:53:57 +02:00
f"Email from {contact.website_email} to {alias.email} is detected as spam",
render(
"transactional/spam-email.txt",
name=user.name,
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
),
render(
"transactional/spam-email.html",
name=user.name,
alias=alias,
website_email=contact.website_email,
disable_alias_link=disable_alias_link,
refused_email_url=refused_email_url,
),
)
def handle_unsubscribe(envelope: Envelope) -> str:
"""return the SMTP status"""
msg = email.message_from_bytes(envelope.original_content)
2020-03-28 23:19:25 +01:00
# format: alias_id:
subject = msg["Subject"]
try:
# subject has the format {alias.id}=
if subject.endswith("="):
alias_id = int(subject[:-1])
# {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)
2020-03-28 23:19:25 +01:00
alias = Alias.get(alias_id)
except Exception:
LOG.warning("Cannot parse alias from subject %s", msg["Subject"])
2020-07-05 16:25:54 +02:00
return "550 SL E8 Wrongly formatted subject"
2020-03-28 23:19:25 +01:00
if not alias:
LOG.warning("No such alias %s", alias_id)
2020-07-05 16:25:54 +02:00
return "550 SL E9 Email not exist"
2020-03-28 23:19:25 +01:00
# This sender cannot unsubscribe
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:
2020-03-28 23:19:25 +01:00
LOG.d("%s cannot disable alias %s", envelope.mail_from, alias)
2020-07-05 16:25:54 +02:00
return "550 SL E10 unauthorized"
2020-03-28 23:19:25 +01:00
# Sender is owner of this alias
alias.enabled = False
db.session.commit()
user = alias.user
enable_alias_url = URL + f"/dashboard/?highlight_alias_id={alias.id}"
2020-05-10 18:23:43 +02:00
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,
),
)
2020-03-28 23:19:25 +01:00
return "250 Unsubscribe request accepted"
def handle_unsubscribe_user(user_id: int, mail_from: str) -> str:
"""return the SMTP status"""
user = User.get(user_id)
if not user:
LOG.exception("No such user %s %s", user_id, mail_from)
return "550 SL E22 so such user"
if mail_from != user.email:
LOG.exception("Unauthorized mail_from %s %s", user, mail_from)
return "550 SL E23 unsubscribe error"
user.notification = False
db.session.commit()
send_email(
user.email,
2020-12-06 13:54:59 +01:00
"You have been unsubscribed from SimpleLogin newsletter",
render(
"transactional/unsubscribe-newsletter.txt",
user=user,
),
render(
"transactional/unsubscribe-newsletter.html",
user=user,
),
)
2020-10-22 12:26:45 +02:00
return "250 Unsubscribe request accepted"
2020-06-10 13:57:23 +02:00
def handle_sender_email(envelope: Envelope):
filename = (
arrow.now().format("YYYY-MM-DD_HH-mm-ss") + "_" + random_string(10) + ".eml"
)
filepath = os.path.join(SENDER_DIR, filename)
with open(filepath, "wb") as f:
f.write(envelope.original_content)
LOG.d("Write email to sender at %s", filepath)
msg = email.message_from_bytes(envelope.original_content)
orig = get_orig_message_from_bounce(msg)
if orig:
LOG.warning(
"Original message %s -> %s saved at %s", orig["From"], orig["To"], filepath
)
return "250 email to sender accepted"
def handle(envelope: Envelope) -> str:
"""Return SMTP status"""
# sanitize mail_from, rcpt_tos
mail_from = envelope.mail_from.lower().strip().replace(" ", "")
rcpt_tos = [
rcpt_to.lower().strip().replace(" ", "") for rcpt_to in envelope.rcpt_tos
]
envelope.mail_from = mail_from
envelope.rcpt_tos = rcpt_tos
# unsubscribe request
if UNSUBSCRIBER and rcpt_tos == [UNSUBSCRIBER]:
LOG.d("Handle unsubscribe request from %s", mail_from)
return handle_unsubscribe(envelope)
2020-06-10 13:57:23 +02:00
# emails sent to sender. Probably bounce emails
if SENDER and rcpt_tos == [SENDER]:
LOG.d("Handle email sent to sender from %s", mail_from)
2020-06-10 13:57:23 +02:00
return handle_sender_email(envelope)
# Whether it's necessary to apply greylisting
if greylisting_needed(mail_from, rcpt_tos):
LOG.warning("Grey listing applied for %s %s", mail_from, rcpt_tos)
return "421 SL Retry later"
# result of all deliveries
# each element is a couple of whether the delivery is successful and the smtp status
res: [(bool, str)] = []
for rcpt_to in rcpt_tos:
if rcpt_to == NOREPLY:
LOG.exception("email sent to noreply address from %s", mail_from)
return "550 SL E25 Email sent to noreply address"
msg = email.message_from_bytes(envelope.original_content)
# Reply case
# recipient starts with "reply+" or "ra+" (ra=reverse-alias) prefix
2020-11-16 19:22:19 +01:00
if is_reply_email(rcpt_to):
2020-11-04 19:42:20 +01:00
LOG.debug("Reply phase %s(%s) -> %s", mail_from, msg["From"], rcpt_to)
is_delivered, smtp_status = handle_reply(envelope, msg, rcpt_to)
res.append((is_delivered, smtp_status))
else: # Forward case
2020-07-23 10:32:10 +02:00
LOG.debug(
2020-11-04 19:42:20 +01:00
"Forward phase %s(%s) -> %s",
mail_from,
2020-07-23 10:32:10 +02:00
msg["From"],
rcpt_to,
)
for is_delivered, smtp_status in handle_forward(envelope, msg, rcpt_to):
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]
async def get_spam_score_async(message: Message) -> float:
2020-09-29 16:00:53 +02:00
LOG.debug("get spam score for %s", message[_MESSAGE_ID])
sa_input = to_bytes(message)
2020-08-16 14:34:50 +02:00
# Spamassassin requires to have an ending linebreak
if not sa_input.endswith(b"\n"):
LOG.d("add linebreak to spamassassin input")
sa_input += b"\n"
2020-08-16 10:22:16 +02:00
try:
2020-08-17 11:41:33 +02:00
# wait for at max 300s which is the default spamd timeout-child
2020-08-16 10:22:16 +02:00
response = await asyncio.wait_for(
2020-09-17 17:03:20 +02:00
aiospamc.check(sa_input, host=SPAMASSASSIN_HOST), timeout=300
2020-08-16 10:22:16 +02:00
)
return response.headers["Spam"].score
except asyncio.TimeoutError:
LOG.exception("SpamAssassin timeout")
2020-08-16 10:22:16 +02:00
# return a negative score so the message is always considered as ham
2020-08-16 14:34:50 +02:00
return -999
except Exception:
LOG.exception("SpamAssassin exception")
return -999
2020-08-15 16:38:16 +02:00
def get_spam_score(message: Message) -> float:
LOG.debug("get spam score for %s", message[_MESSAGE_ID])
sa_input = to_bytes(message)
# Spamassassin requires to have an ending linebreak
if not sa_input.endswith(b"\n"):
LOG.d("add linebreak to spamassassin input")
sa_input += b"\n"
try:
2020-09-30 14:03:19 +02:00
# wait for at max 300s which is the default spamd timeout-child
sa = SpamAssassin(sa_input, host=SPAMASSASSIN_HOST, timeout=300)
2020-12-02 12:40:29 +01:00
score = sa.get_score()
LOG.d("SA report, score %s. %s", score, sa.get_report_json())
return score
except Exception:
LOG.exception("SpamAssassin exception")
# return a negative score so the message is always considered as ham
return -999
2020-11-25 14:43:02 +01:00
def sl_sendmail(
from_addr, to_addr, msg: Message, mail_options, rcpt_options, can_retry=True
):
"""replace smtp.sendmail"""
if POSTFIX_SUBMISSION_TLS:
smtp = SMTP(POSTFIX_SERVER, 587)
smtp.starttls()
else:
smtp = SMTP(POSTFIX_SERVER, POSTFIX_PORT or 25)
2020-11-25 14:56:54 +01:00
# smtp.send_message has UnicodeEncodeError
# encode message raw directly instead
2020-11-25 14:43:02 +01:00
try:
smtp.sendmail(
from_addr,
to_addr,
to_bytes(msg),
mail_options,
rcpt_options,
)
except SMTPServerDisconnected:
if can_retry:
LOG.warning("SMTPServerDisconnected error, retry")
2020-11-25 14:56:54 +01:00
time.sleep(3)
2020-11-25 14:43:02 +01:00
sl_sendmail(
from_addr, to_addr, msg, mail_options, rcpt_options, can_retry=False
)
else:
raise
class MailHandler:
async def handle_DATA(self, server, session, envelope: Envelope):
2020-08-17 11:40:58 +02:00
try:
ret = self._handle(envelope)
2020-08-17 11:40:58 +02:00
return ret
except Exception:
LOG.exception(
2020-08-27 10:20:48 +02:00
"email handling fail %s -> %s",
envelope.mail_from,
envelope.rcpt_tos,
2020-08-17 11:40:58 +02:00
)
return "421 SL Retry later"
def _handle(self, envelope: Envelope):
start = time.time()
LOG.info(
"===>> New message, mail from %s, rctp tos %s ",
envelope.mail_from,
envelope.rcpt_tos,
)
app = new_app()
with app.app_context():
ret = handle(envelope)
LOG.info("takes %s seconds <<===", time.time() - start)
return ret
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.warning("LOAD PGP keys")
app = create_app()
with app.app_context():
load_pgp_public_keys()
while True:
time.sleep(2)
def asyncio_main(port: int):
"""
Main entrypoint using asyncio directly without passing by aiosmtpd Controller
"""
if LOAD_PGP_EMAIL_HANDLER:
LOG.warning("LOAD PGP keys")
app = create_app()
with app.app_context():
2020-06-07 12:46:59 +02:00
load_pgp_public_keys()
2020-08-17 11:39:13 +02:00
loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)
2020-08-17 11:40:58 +02:00
lock = asyncio.Lock()
handler = MailHandler(lock)
2020-08-17 11:39:13 +02:00
def factory():
return aiosmtpd.smtp.SMTP(handler, enable_SMTPUTF8=True)
server = loop.run_until_complete(
loop.create_server(factory, host="0.0.0.0", port=port)
2020-08-17 11:39:13 +02:00
)
try:
loop.run_forever()
except KeyboardInterrupt:
pass
# Close the server
LOG.info("Close SMTP server")
server.close()
loop.run_until_complete(server.wait_closed())
loop.close()
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.info("Listen for port %s", args.port)
main(port=args.port)