[FW][FIX] mail: correctly check all recipients when routing on aliases

/!\ This commit is a manual forward-port of two PR targetting originally
11.0: #40442 and its fix / partial revert #41042. /!\

Purpose of this commit is to check all recipients of incoming emails when
trying to determine the route to apply. Notably

  * an incoming email should be considered as a write to catchall only if all
    recipients are catchall. Catchall + a valid alias should take the alias
    into account;
  * an incoming email sent to the bounce alias should be considered as a bounce
    even if another valid alias is in recipients and whatever the order. Indeed
    it indicates an issue and bounce is considered as more important;
  * forward to an alias linked to another model should check all recipients
    and not only the first one. Otherwise reply_alias, forward_alias is
    considered as a reply whereas it should be considered as a forward when
    considering all recipients;

Tests are added according to those specifications.

Please see original PRs for more details about the content, the comments
done on it and the various discussions.

PR #46764
Task ID 2121551

X-original-commit: df00bd2d3bddf9a2b56e8554380669025e146d21

1 files changed, 20 insertions, 10 deletions

diff --git a/addons/mail/models/mail_thread.py b/addons/mail/models/mail_thread.py
index 55b1c12aeef..bfa5bbe6f19 100644
--- a/addons/mail/models/mail_thread.py
+++ b/addons/mail/models/mail_thread.py
@@ -980,10 +980,16 @@ class MailThread(models.AbstractModel):
         email_from = message_dict['email_from']
         email_from_localpart = (tools.email_split(email_from) or [''])[0].split('@', 1)[0].lower()
         email_to = message_dict['to']
-        email_to_localpart = (tools.email_split(email_to) or [''])[0].split('@', 1)[0].lower()
+        email_to_localparts = [
+            e.split('@', 1)[0].lower()
+            for e in (tools.email_split(email_to) or [''])
+        ]
         # Delivered-To is a safe bet in most modern MTAs, but we have to fallback on To + Cc values
         # for all the odd MTAs out there, as there is no standard header for the envelope's `rcpt_to` value.
-        rcpt_tos_localparts = [e.split('@')[0].lower() for e in tools.email_split(message_dict['recipients'])]
+        rcpt_tos_localparts = [
+            e.split('@')[0].lower()
+            for e in tools.email_split(message_dict['recipients'])
+        ]
 
         # 0. Handle bounce: verify whether this is a bounced email and use it to collect bounce data and update notifications for customers
         #    Bounce regex: typical form of bounce is bounce_alias+128-crm.lead-34@domain
@@ -993,7 +999,7 @@ class MailThread(models.AbstractModel):
         #        As all MTA does not respect this RFC (googlemail is one of them),
         #       we also need to verify if the message come from "mailer-daemon"
         #    If not a bounce: reset bounce information
-        if bounce_alias and bounce_alias in email_to_localpart:
+        if bounce_alias and any(email.startswith(bounce_alias) for email in email_to_localparts):
             bounce_re = re.compile("%s\+(\d+)-?([\w.]+)?-?(\d+)?" % re.escape(bounce_alias), re.UNICODE)
             bounce_match = bounce_re.search(email_to)
             if bounce_match:
@@ -1008,15 +1014,19 @@ class MailThread(models.AbstractModel):
         #    if destination = alias with different model -> consider it is a forward and not a reply
         #    if destination = alias with same model -> check contact settings as they still apply
         if reply_model and reply_thread_id:
-            other_alias = self.env['mail.alias'].search([
-                '&',
+            alias_count = self.env['mail.alias'].search_count([
+                '&', '&',
                 ('alias_name', '!=', False),
-                ('alias_name', '=', email_to_localpart)
+                ('alias_name', 'in', email_to_localparts),
+                ('alias_model_id.model', '!=', reply_model),
             ])
-            if other_alias and other_alias.alias_model_id.model != reply_model:
-                is_a_reply = False
+            is_a_reply = alias_count == 0
+
         if is_a_reply:
-            dest_aliases = self.env['mail.alias'].search([('alias_name', 'in', rcpt_tos_localparts)], limit=1)
+            dest_aliases = self.env['mail.alias'].search([
+                ('alias_name', 'in', rcpt_tos_localparts),
+                ('alias_model_id.model', '=', reply_model)
+            ], limit=1)
 
             user_id = self._mail_find_user_for_gateway(email_from, alias=dest_aliases).id or self._uid
             route = self._routing_check_route(
@@ -1037,7 +1047,7 @@ class MailThread(models.AbstractModel):
             message_dict.pop('parent_id', None)
 
             # check it does not directly contact catchall
-            if catchall_alias and catchall_alias in email_to_localpart:
+            if catchall_alias and all(email_localpart == catchall_alias for email_localpart in email_to_localparts):
                 _logger.info('Routing mail from %s to %s with Message-Id %s: direct write to catchall, bounce', email_from, email_to, message_id)
                 body = self.env.ref('mail.mail_bounce_catchall').render({
                     'message': message,