use VERP: send email from bounce address
This commit is contained in:
Son NK
parent
c83b146f14
commit
f1e9b2b5d7
196
email_handler.py
196
email_handler.py
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@ -79,6 +79,9 @@ from app.config import (
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PGP_SENDER_PRIVATE_KEY,
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ALERT_BOUNCE_EMAIL_REPLY_PHASE,
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NOREPLY,
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BOUNCE_EMAIL,
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BOUNCE_PREFIX,
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BOUNCE_SUFFIX,
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)
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from app.email_utils import (
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send_email,
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@ -95,7 +98,6 @@ from app.email_utils import (
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get_email_domain_part,
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copy,
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to_bytes,
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get_header_from_bounce,
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send_email_at_most_times,
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is_valid_alias_address_domain,
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should_add_dkim_signature,
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@ -107,6 +109,7 @@ from app.email_utils import (
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is_valid_email,
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replace,
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should_disable,
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get_header_from_bounce,
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)
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from app.extensions import db
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from app.greylisting import greylisting_needed
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@ -720,7 +723,8 @@ def forward_email_to_mailbox(
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try:
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sl_sendmail(
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contact.reply_email,
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# use a different envelope sender for each forward (aka VERP)
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BOUNCE_EMAIL.format(email_log.id),
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mailbox.email,
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msg,
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envelope.mail_options,
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@ -795,7 +799,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
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user,
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)
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handle_bounce(contact, alias, msg, user)
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handle_bounce_deprecated(contact, alias, msg, user)
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return False, "550 SL E6"
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# Anti-spoofing
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@ -951,7 +955,8 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
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try:
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sl_sendmail(
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alias.email,
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# VERP
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BOUNCE_EMAIL.format(email_log.id),
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contact.website_email,
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msg,
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envelope.mail_options,
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@ -1124,7 +1129,7 @@ def handle_unknown_mailbox(
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)
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def handle_bounce(contact: Contact, alias: Alias, msg: Message, user: User):
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def handle_bounce_deprecated(contact: Contact, alias: Alias, msg: Message, user: User):
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"""
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Handle bounce that is sent to the reverse-alias
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Happens when an email cannot be forwarded to a mailbox
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@ -1260,41 +1265,138 @@ def handle_bounce(contact: Contact, alias: Alias, msg: Message, user: User):
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)
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def handle_bounce_reply_phase(msg: Message, rcpt_to: str):
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def handle_bounce_forward_phase(msg: Message, email_log: EmailLog):
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"""
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Handle bounce that is sent to alias
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Happens when an email cannot be sent from an alias to a contact
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Handle forward phase bounce
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Happens when an email cannot be sent to a mailbox
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"""
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alias = Alias.get_by(email=rcpt_to)
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# the alias has been deleted in the meantime
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if not alias:
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LOG.warning("No such alias for %s", rcpt_to)
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return
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LOG.debug("Handle bounce during forward phase for %s", email_log)
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contact = email_log.contact
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alias = contact.alias
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user = alias.user
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try:
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email_log_id = int(get_header_from_bounce(msg, _EMAIL_LOG_ID_HEADER))
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except Exception:
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# save the data for debugging
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# todo: remove.
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file_path = f"/tmp/{random_string(10)}.eml"
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with open(file_path, "wb") as f:
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f.write(to_bytes(msg))
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# Store the bounced email, generate a name for the email
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random_name = str(uuid.uuid4())
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LOG.exception(
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"Cannot get email-log-id from bounced report, %s %s %s",
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full_report_path = f"refused-emails/full-{random_name}.eml"
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s3.upload_email_from_bytesio(full_report_path, BytesIO(to_bytes(msg)), random_name)
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file_path = None
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orig_msg = get_orig_message_from_bounce(msg)
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if not orig_msg:
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# Some MTA does not return the original message in bounce message
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# nothing we can do here
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LOG.warning(
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"Cannot parse original message from bounce message %s %s %s %s",
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alias,
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user,
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file_path,
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contact,
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full_report_path,
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)
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return
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else:
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file_path = f"refused-emails/{random_name}.eml"
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s3.upload_email_from_bytesio(file_path, BytesIO(to_bytes(msg)), random_name)
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email_log = EmailLog.get(email_log_id)
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contact = email_log.contact
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refused_email = RefusedEmail.create(
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path=file_path, full_report_path=full_report_path, user_id=user.id
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)
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db.session.flush()
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LOG.d("Create refused email %s", refused_email)
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mailbox = email_log.mailbox
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# email_log.mailbox should be set during the forward phase
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if not mailbox:
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LOG.exception("Use %s default mailbox %s", alias, refused_email)
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mailbox = alias.mailbox
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email_log.bounced = True
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email_log.refused_email_id = refused_email.id
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email_log.bounced_mailbox_id = mailbox.id
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db.session.commit()
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refused_email_url = f"{URL}/dashboard/refused_email?highlight_id={email_log.id}"
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nb_bounced = EmailLog.filter_by(contact_id=contact.id, bounced=True).count()
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if nb_bounced >= 2 and alias.cannot_be_disabled:
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LOG.warning("%s cannot be disabled", alias)
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# inform user of this bounce
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if not should_disable(alias):
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LOG.d(
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"Inform user %s about a bounce from contact %s to alias %s",
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user,
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contact,
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alias,
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)
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disable_alias_link = f"{URL}/dashboard/unsubscribe/{alias.id}"
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send_email_with_rate_control(
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user,
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ALERT_BOUNCE_EMAIL,
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user.email,
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f"Email from {contact.website_email} to {alias.email} cannot be delivered to your mailbox",
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render(
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"transactional/bounce/bounced-email.txt",
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alias=alias,
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website_email=contact.website_email,
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disable_alias_link=disable_alias_link,
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refused_email_url=refused_email_url,
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mailbox_email=mailbox.email,
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),
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render(
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"transactional/bounce/bounced-email.html",
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alias=alias,
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website_email=contact.website_email,
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disable_alias_link=disable_alias_link,
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refused_email_url=refused_email_url,
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mailbox_email=mailbox.email,
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),
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max_nb_alert=10,
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)
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else:
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LOG.warning(
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"Disable alias %s now",
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alias,
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)
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alias.enabled = False
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db.session.commit()
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send_email_with_rate_control(
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user,
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ALERT_BOUNCE_EMAIL,
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user.email,
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f"Alias {alias.email} has been disabled due to second undelivered email from {contact.website_email}",
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render(
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"transactional/bounce/automatic-disable-alias.txt",
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alias=alias,
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website_email=contact.website_email,
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refused_email_url=refused_email_url,
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mailbox_email=mailbox.email,
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),
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render(
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"transactional/bounce/automatic-disable-alias.html",
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alias=alias,
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website_email=contact.website_email,
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refused_email_url=refused_email_url,
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mailbox_email=mailbox.email,
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),
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max_nb_alert=10,
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)
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def handle_bounce_reply_phase(msg: Message, email_log: EmailLog):
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"""
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Handle reply phase bounce
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Happens when an email cannot be sent from an alias to a contact
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"""
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LOG.debug("Handle bounce during reply phase for %s", email_log)
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contact = email_log.contact
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alias = contact.alias
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user = alias.user
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# Store the bounced email
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# generate a name for the email
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random_name = str(uuid.uuid4())
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@ -1580,6 +1682,13 @@ def handle(envelope: Envelope) -> str:
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LOG.d("Handle email sent to sender from %s", mail_from)
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return handle_sender_email(envelope)
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if (
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len(rcpt_tos) == 1
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and rcpt_tos[0].startswith(BOUNCE_PREFIX)
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and rcpt_tos[0].endswith(BOUNCE_SUFFIX)
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):
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return handle_bounce(envelope, rcpt_tos[0])
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# Whether it's necessary to apply greylisting
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if greylisting_needed(mail_from, rcpt_tos):
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LOG.warning("Grey listing applied for %s %s", mail_from, rcpt_tos)
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@ -1602,18 +1711,6 @@ def handle(envelope: Envelope) -> str:
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LOG.debug("Reply phase %s(%s) -> %s", mail_from, msg["From"], rcpt_to)
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is_delivered, smtp_status = handle_reply(envelope, msg, rcpt_to)
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res.append((is_delivered, smtp_status))
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# bounce email initiated by Postfix
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# can happen in case an email cannot be sent from an alias to a contact
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# in this case Postfix will send a bounce report to original sender, which is the alias
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elif mail_from == "<>":
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LOG.warning(
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"Handle bounce sent to alias %s",
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rcpt_to,
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)
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handle_bounce_reply_phase(msg, rcpt_to)
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return "550 SL E24 Email cannot be sent to contact"
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else: # Forward case
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LOG.debug(
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"Forward phase %s(%s) -> %s",
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@ -1633,6 +1730,27 @@ def handle(envelope: Envelope) -> str:
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return res[0][1]
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def handle_bounce(envelope, rcpt_to) -> str:
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"""
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Return SMTP status, e.g. "500 Error"
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"""
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LOG.d("handle bounce sent to %s", rcpt_to)
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msg = email.message_from_bytes(envelope.original_content)
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# parse the EmailLog
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email_log_id = rcpt_to[len("bounces+") : rcpt_to.find("@")]
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email_log_id = int(email_log_id)
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email_log = EmailLog.get(email_log_id)
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if email_log.is_reply:
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handle_bounce_reply_phase(msg, email_log)
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return "550 SL E24 Email cannot be sent to contact"
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else: # forward phase
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handle_bounce_forward_phase(msg, email_log)
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return "550 SL E26 Email cannot be forwarded to mailbox"
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async def get_spam_score_async(message: Message) -> float:
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sa_input = to_bytes(message)
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