refactor: put all SMTP statuses into status.py

app/email/status.py

@@ -0,0 +1,39 @@
+# 2** status
+E200 = "250 Message accepted for delivery"
+E201 = "250 SL E201"
+E202 = "250 Unsubscribe request accepted"
+E203 = "250 SL E203 email can't be sent from a reverse-alias"
+E204 = "250 SL E204 ignore"
+E205 = "250 SL E205 bounce handled"
+# out of office status
+E206 = "250 SL E206 Out of office"
+
+# 4** errors
+E401 = "421 SL E401 Retry later"
+E402 = "421 SL E402 Retry later"
+E403 = "421 SL E403 Retry later"
+E404 = "421 SL E404 Retry later"
+E405 = "421 SL E405 Retry later"
+E406 = "421 SL E406 Retry later"
+
+# 5** errors
+E501 = "550 SL E501"
+E502 = "550 SL E502 Email not exist"
+E503 = "550 SL E503"
+E504 = "550 SL E504 Account disabled"
+E505 = "550 SL E505"
+E506 = "550 SL E506 Email detected as spam"
+E507 = "550 SL E507 Wrongly formatted subject"
+E508 = "550 SL E508 Email not exist"
+E509 = "550 SL E509 unauthorized"
+E510 = "550 SL E510 so such user"
+E511 = "550 SL E511 unsubscribe error"
+E512 = "550 SL E512 No such email log"
+E513 = "550 SL E513 Email cannot be forwarded to mailbox"
+E514 = "550 SL E514 Email sent to noreply address"
+E515 = "550 SL E515 Email not exist"
+E516 = "550 SL E516 invalid mailbox"
+E517 = "550 SL E517 unverified mailbox"
+E518 = "550 SL E518 Disabled mailbox"
+E519 = "550 SL E519 Email detected as spam"
+E520 = "550 SL E24 Email cannot be sent to contact"

email_handler.py

@@ -75,6 +75,7 @@ from app.config import (
     ENABLE_SPAM_ASSASSIN,
     BOUNCE_PREFIX_FOR_REPLY_PHASE,
 )
+from app.email import status
 from app.email.spam import get_spam_score
 from app.email_utils import (
     send_email,
@@ -485,13 +486,13 @@ def handle_forward(envelope, msg: Message, rcpt_to: str) -> List[Tuple[bool, str
         alias = try_auto_create(address)
         if not alias:
             LOG.d("alias %s cannot be created on-the-fly, return 550", address)
-            return [(False, "550 SL E3 Email not exist")]
+            return [(False, status.E515)]
 
     user = alias.user
 
     if user.disabled:
         LOG.w("User %s disabled, disable forwarding emails for %s", user, alias)
-        return [(False, "550 SL E20 Account disabled")]
+        return [(False, status.E504)]
 
     # mail_from = envelope.mail_from
     # for mb in alias.mailboxes:
@@ -518,20 +519,20 @@ def handle_forward(envelope, msg: Message, rcpt_to: str) -> List[Tuple[bool, str
         )
         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")]
+        return [(True, status.E200)]
 
     ret = []
     mailboxes = alias.mailboxes
 
     # no valid mailbox
     if not mailboxes:
-        return [(False, "550 SL E16 invalid mailbox")]
+        return [(False, status.E516)]
 
     # no need to create a copy of message
     for mailbox in mailboxes:
         if not mailbox.verified:
             LOG.d("%s unverified, do not forward", mailbox)
-            ret.append((False, "550 SL E19 unverified mailbox"))
+            ret.append((False, status.E517))
         else:
             # create a copy of message for each forward
             ret.append(
@@ -560,7 +561,7 @@ def forward_email_to_mailbox(
 
     if mailbox.disabled:
         LOG.debug("%s disabled, do not forward")
-        return False, "550 SL E21 Disabled mailbox"
+        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):
@@ -593,7 +594,7 @@ def forward_email_to_mailbox(
 
         # retry later
         # so when user fixes the mailbox, the email can be delivered
-        return False, "421 SL E14"
+        return False, status.E405
 
     email_log = EmailLog.create(
         contact_id=contact.id, user_id=user.id, mailbox_id=mailbox.id, commit=True
@@ -641,7 +642,7 @@ def forward_email_to_mailbox(
             db.session.commit()
 
             handle_spam(contact, alias, msg, user, mailbox, email_log)
-            return False, "550 SL E1 Email detected as spam"
+            return False, status.E519
 
     if contact.invalid_email:
         LOG.d("add noreply information %s %s", alias, mailbox)
@@ -684,11 +685,11 @@ def forward_email_to_mailbox(
                 msg, mailbox.pgp_finger_print, mailbox.pgp_public_key, can_sign=True
             )
         except PGPException:
-            LOG.exception(
+            LOG.e(
                 "Cannot encrypt message %s -> %s. %s %s", contact, alias, mailbox, user
             )
             # so the client can retry later
-            return False, "421 SL E12 Retry later"
+            return False, status.E406
 
     # add custom header
     add_or_replace_header(msg, _DIRECTION, "Forward")
@@ -750,10 +751,10 @@ def forward_email_to_mailbox(
             alias,
             mailbox,
         )
-        return False, "421 SL E17 Retry later"
+        return False, status.E401
     else:
         db.session.commit()
-        return True, "250 Message accepted for delivery"
+        return True, status.E200
 
 
 def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
@@ -766,7 +767,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
     # 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, "550 SL E2"
+        return False, status.E501
 
     # handle case where reply email is generated with non-allowed char
     reply_email = normalize_reply_email(reply_email)
@@ -774,7 +775,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
     contact = Contact.get_by(reply_email=reply_email)
     if not contact:
         LOG.w(f"No such forward-email with {reply_email} as reply-email")
-        return False, "550 SL E4 Email not exist"
+        return False, status.E502
 
     alias = contact.alias
     address: str = contact.alias.email
@@ -784,7 +785,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
     # 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"
+        return False, status.E503
 
     user = alias.user
     mail_from = envelope.mail_from
@@ -796,7 +797,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
             alias,
             contact,
         )
-        return [(False, "550 SL E20 Account disabled")]
+        return [(False, status.E504)]
 
     # Anti-spoofing
     mailbox = get_mailbox_from_mail_from(mail_from, alias)
@@ -813,12 +814,13 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
         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"
+            return False, status.E505
 
     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. 5** because that generates bounce report
+            # cannot use 4** here as sender will retry.
-            return True, "250 SL E11"
+            # cannot use 5** because that generates bounce report
+            return True, status.E201
 
     email_log = EmailLog.create(
         contact_id=contact.id,
@@ -870,7 +872,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
             db.session.commit()
 
             handle_spam(contact, alias, msg, user, mailbox, email_log, is_reply=True)
-            return False, "550 SL E15 Email detected as spam"
+            return False, status.E506
 
     delete_all_headers_except(
         msg,
@@ -907,7 +909,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
             EmailLog.delete(email_log.id)
             db.session.commit()
             # return 421 so the client can retry later
-            return False, "421 SL E13 Retry later"
+            return False, status.E402
 
     db.session.commit()
 
@@ -991,8 +993,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
         )
 
     # return 250 even if error as user is already informed of the incident and can retry sending the email
-
+    return True, status.E200
-    return True, "250 Message accepted for delivery"
 
 
 def get_mailbox_from_mail_from(mail_from: str, alias) -> Optional[Mailbox]:
@@ -1262,7 +1263,7 @@ def handle_bounce_reply_phase(envelope, msg: Message, email_log: EmailLog):
             refused_email_url=refused_email_url,
         ),
     )
-    return "550 SL E24 Email cannot be sent to contact"
+    return status.E520
 
 
 def handle_spam(
@@ -1381,11 +1382,11 @@ def handle_unsubscribe(envelope: Envelope, msg: Message) -> str:
         alias = Alias.get(alias_id)
     except Exception:
         LOG.w("Cannot parse alias from subject %s", msg["Subject"])
-        return "550 SL E8 Wrongly formatted subject"
+        return status.E507
 
     if not alias:
         LOG.w("No such alias %s", alias_id)
-        return "550 SL E9 Email not exist"
+        return status.E508
 
     # This sender cannot unsubscribe
     mail_from = envelope.mail_from
@@ -1393,7 +1394,7 @@ def handle_unsubscribe(envelope: Envelope, msg: Message) -> str:
     mailbox = get_mailbox_from_mail_from(mail_from, alias)
     if not mailbox:
         LOG.d("%s cannot disable alias %s", envelope.mail_from, alias)
-        return "550 SL E10 unauthorized"
+        return status.E509
 
     # Sender is owner of this alias
     alias.enabled = False
@@ -1419,7 +1420,7 @@ def handle_unsubscribe(envelope: Envelope, msg: Message) -> str:
             ),
         )
 
-    return "250 Unsubscribe request accepted"
+    return status.E202
 
 
 def handle_unsubscribe_user(user_id: int, mail_from: str) -> str:
@@ -1427,11 +1428,11 @@ def handle_unsubscribe_user(user_id: int, mail_from: str) -> str:
     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"
+        return status.E510
 
     if mail_from != user.email:
         LOG.exception("Unauthorized mail_from %s %s", user, mail_from)
-        return "550 SL E23 unsubscribe error"
+        return status.E511
 
     user.notification = False
     db.session.commit()
@@ -1449,7 +1450,7 @@ def handle_unsubscribe_user(user_id: int, mail_from: str) -> str:
         ),
     )
 
-    return "250 Unsubscribe request accepted"
+    return status.E202
 
 
 def handle_transactional_bounce(envelope: Envelope, rcpt_to):
@@ -1472,7 +1473,7 @@ def handle_bounce(envelope, email_log: EmailLog, msg: Message) -> str:
 
     if not email_log:
         LOG.w("No such email log")
-        return "550 SL E27 No such email log"
+        return status.E512
 
     contact: Contact = email_log.contact
     alias = contact.alias
@@ -1524,7 +1525,7 @@ def handle_bounce(envelope, email_log: EmailLog, msg: Message) -> str:
         return handle_bounce_reply_phase(envelope, msg, email_log)
     else:  # forward phase
         handle_bounce_forward_phase(msg, email_log)
-        return "550 SL E26 Email cannot be forwarded to mailbox"
+        return status.E513
 
 
 def should_ignore(mail_from: str, rcpt_tos: List[str]) -> bool:
@@ -1556,7 +1557,7 @@ def handle(envelope: Envelope) -> str:
 
     if should_ignore(mail_from, rcpt_tos):
         LOG.e("Ignore email mail_from=%s rcpt_to=%s", mail_from, rcpt_tos)
-        return "250 email can't be sent from a reverse-alias"
+        return status.E204
 
     # sanitize email headers
     sanitize_header(msg, "from")
@@ -1584,7 +1585,7 @@ def handle(envelope: Envelope) -> str:
             contact.alias,
             contact.website_email,
         )
-        return "250 email can't be sent from a reverse-alias"
+        return status.E203
 
     # unsubscribe request
     if UNSUBSCRIBER and rcpt_tos == [UNSUBSCRIBER]:
@@ -1599,7 +1600,7 @@ def handle(envelope: Envelope) -> str:
     ):
         LOG.d("Handle email sent to sender from %s", mail_from)
         handle_transactional_bounce(envelope, rcpt_tos[0])
-        return "250 bounce handled"
+        return status.E205
 
     # Handle bounce
     if (
@@ -1638,7 +1639,7 @@ def handle(envelope: Envelope) -> str:
     # Whether it's necessary to apply greylisting
     if greylisting_needed(mail_from, rcpt_tos):
         LOG.w("Grey listing applied for mail_from:%s rcpt_tos:%s", mail_from, rcpt_tos)
-        return "421 SL Retry later"
+        return status.E403
 
     # Handle "out of office" auto notice. An automatic response is sent for every forwarded email
     # todo: remove logging
@@ -1646,7 +1647,7 @@ def handle(envelope: Envelope) -> str:
         LOG.w(
             "out-of-office email to reverse alias %s. %s", rcpt_tos[0], msg.as_string()
         )
-        return "250 SL E28"
+        return status.E206
 
     # result of all deliveries
     # each element is a couple of whether the delivery is successful and the smtp status
@@ -1656,7 +1657,7 @@ def handle(envelope: Envelope) -> str:
     for rcpt_index, rcpt_to in enumerate(rcpt_tos):
         if rcpt_to == NOREPLY:
             LOG.e("email sent to noreply address from %s", mail_from)
-            return "550 SL E25 Email sent to noreply address"
+            return status.E514
 
         # create a copy of msg for each recipient except the last one
         # as copy() is a slow function
@@ -1704,7 +1705,7 @@ class MailHandler:
                 envelope.mail_from,
                 envelope.rcpt_tos,
             )
-            return "421 SL Retry later"
+            return status.E404
 
     def _handle(self, envelope: Envelope):
         start = time.time()