diff --git a/addons/mail/models/mail_thread.py b/addons/mail/models/mail_thread.py
index 830b82e4c6f..f79e8d2ada2 100644
--- a/addons/mail/models/mail_thread.py
+++ b/addons/mail/models/mail_thread.py
@@ -1143,6 +1143,9 @@ class MailThread(models.AbstractModel):
                 thread_id = thread.id
                 subtype_id = thread._creation_subtype().id
 
+            # switch to odoobot for all incoming message creation
+            # to have a priviledged archived user so real_author_id is correctly computed
+            thread_root = thread.with_user(self.env.ref('base.user_root'))
             # replies to internal message are considered as notes, but parent message
             # author is added in recipients to ensure they are notified of a private answer
             parent_message = False
@@ -1162,13 +1165,13 @@ class MailThread(models.AbstractModel):
             for x in ('from', 'to', 'cc', 'recipients', 'references', 'in_reply_to', 'is_bounce', 'bounced_email', 'bounced_message', 'bounced_msg_ids', 'bounced_partner'):
                 post_params.pop(x, None)
             new_msg = False
-            if thread._name == 'mail.thread':  # message with parent_id not linked to record
-                new_msg = thread.message_notify(**post_params)
+            if thread_root._name == 'mail.thread':  # message with parent_id not linked to record
+                new_msg = thread_root.message_notify(**post_params)
             else:
                 # parsing should find an author independently of user running mail gateway, and ensure it is not odoobot
                 partner_from_found = message_dict.get('author_id') and message_dict['author_id'] != self.env['ir.model.data']._xmlid_to_res_id('base.partner_root')
-                thread = thread.with_context(mail_create_nosubscribe=not partner_from_found)
-                new_msg = thread.message_post(**post_params)
+                thread_root = thread_root.with_context(mail_create_nosubscribe=not partner_from_found)
+                new_msg = thread_root.message_post(**post_params)
 
             if new_msg and original_partner_ids:
                 # postponed after message_post, because this is an external message and we don't want to create
diff --git a/addons/mail/tests/common.py b/addons/mail/tests/common.py
index 055eb69de80..48f01f3cf88 100644
--- a/addons/mail/tests/common.py
+++ b/addons/mail/tests/common.py
@@ -132,7 +132,7 @@ class MockEmail(common.BaseCase, MockSmtplibCase):
     def format_and_process(self, template, email_from, to, subject='Frogs', cc='',
                            return_path='', extra='',  msg_id=False,
                            model=None, target_model='mail.test.gateway', target_field='name',
-                           **kwargs):
+                           with_user=None, **kwargs):
         self.assertFalse(self.env[target_model].search([(target_field, '=', subject)]))
         if not msg_id:
             msg_id = "<%.7f-test@iron.sky>" % (time.time())
@@ -142,7 +142,7 @@ class MockEmail(common.BaseCase, MockSmtplibCase):
                            email_from=email_from, msg_id=msg_id,
                            **kwargs)
         # In real use case, fetched mail processing is executed with administrative right.
-        self.env['mail.thread'].sudo().message_process(model, mail)
+        self.env['mail.thread'].with_user(with_user or self.env.user).sudo().message_process(model, mail)
         return self.env[target_model].search([(target_field, '=', subject)])
 
     def gateway_reply_wrecord(self, template, record, use_in_reply_to=True):
diff --git a/addons/test_mail/tests/test_mail_gateway.py b/addons/test_mail/tests/test_mail_gateway.py
index 75f144db9ef..8c8ab81a3bc 100644
--- a/addons/test_mail/tests/test_mail_gateway.py
+++ b/addons/test_mail/tests/test_mail_gateway.py
@@ -2,6 +2,7 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 import base64
+import itertools
 import socket
 
 from datetime import datetime
@@ -354,6 +355,61 @@ class TestMailgateway(MailCommon):
         self.assertFalse(record.message_ids[0].author_id)
         self.assertEqual(record.message_ids[0].email_from, from_1.email_formatted)
 
+    @mute_logger('odoo.addons.mail.models.mail_thread', 'odoo.models')
+    def test_message_route_alias_owner_author_notify(self):
+        """ Make sure users are notified when a reply is sent to an alias address.
+        Alias owner should impact the message creator, but not notifications. """
+        test_record = self.env['mail.test.ticket'].create({})
+        author_partner = self.env['res.partner'].create({
+            'name': 'Author',
+            'email': 'author-partner@test.com',
+        })
+        message = self.env['mail.message'].create({
+            'body': '<p>test</p>',
+            'email_from': 'author-partner@test.com',  # email sent by author who also has an alias with their email
+            'message_type': 'email',
+            'model': test_record._name,
+            'res_id': test_record.id,
+        })
+        self.env['mail.alias'].create({
+            'alias_model_id': self.env['ir.model']._get_id(test_record._name),
+            'alias_name': 'author-partner',
+            'alias_user_id': self.user_employee.id
+        })
+
+        test_record.message_subscribe((author_partner | self.user_employee.partner_id).ids)
+
+        messages = test_record.message_ids
+
+        self.assertFalse(self.user_root.active, 'notification logic relies on odoobot being archived')
+
+        test_users = [self.user_employee, self.user_root]
+        email_tos = ['author-partner@test.com', 'some_non_aliased_email@test.com']
+        for email_to, test_user in itertools.product(email_tos, test_users):
+            with self.subTest(test_user=test_user, email_to=email_to):
+                with self.mock_mail_gateway(), self.mock_mail_app():
+                    self.format_and_process(
+                        MAIL_TEMPLATE, self.email_from, email_to,
+                        subject=message.message_id, extra=f'In-Reply-To:\r\n\t{message.message_id}\n',
+                        model=None, with_user=test_user)
+                new_messages = test_record.message_ids - messages
+
+                self.assertEqual(len(new_messages), 1)
+                self.assertEqual(new_messages.create_uid, self.user_root,
+                                 'Odoobot should be creating the message')
+
+                # Make sure the alias owner is notified if they are a follower
+                self.assertNotified(new_messages, [{
+                    'partner': self.user_employee.partner_id,
+                    'is_read': False,
+                    'type': 'inbox',
+                }])
+                # never notify the author of the incoming message
+                with self.assertRaises(Exception):
+                    self.assertNotified(new_messages, [{'partner': author_partner}])
+
+            messages = test_record.message_ids
+
     # --------------------------------------------------
     # Alias configuration
     # --------------------------------------------------
@@ -626,7 +682,7 @@ class TestMailgateway(MailCommon):
             record = self.format_and_process(MAIL_TEMPLATE, self.user_employee.email_formatted, f'groups@{self.alias_domain}', subject='NoEmployeeAllowed')
         self.assertEqual(record.create_uid, self.user_employee)
         self.assertEqual(record.message_ids[0].subject, 'NoEmployeeAllowed')
-        self.assertEqual(record.message_ids[0].create_uid, self.user_employee)
+        self.assertEqual(record.message_ids[0].create_uid, self.user_root, 'Message should be created by caller of message_process.')
         self.assertEqual(record.message_ids[0].author_id, self.user_employee.partner_id)
 
     @mute_logger('odoo.addons.mail.models.mail_thread')
@@ -634,19 +690,19 @@ class TestMailgateway(MailCommon):
         record = self.format_and_process(MAIL_TEMPLATE, self.user_employee.email_formatted, f'groups@{self.alias_domain}', subject='Email Found')
         self.assertEqual(record.create_uid, self.user_employee)
         self.assertEqual(record.message_ids[0].subject, 'Email Found')
-        self.assertEqual(record.message_ids[0].create_uid, self.user_employee)
+        self.assertEqual(record.message_ids[0].create_uid, self.user_root)
         self.assertEqual(record.message_ids[0].author_id, self.user_employee.partner_id)
 
         record = self.format_and_process(MAIL_TEMPLATE, 'Another name <%s>' % self.user_employee.email, f'groups@{self.alias_domain}', subject='Email OtherName')
         self.assertEqual(record.create_uid, self.user_employee)
         self.assertEqual(record.message_ids[0].subject, 'Email OtherName')
-        self.assertEqual(record.message_ids[0].create_uid, self.user_employee)
+        self.assertEqual(record.message_ids[0].create_uid, self.user_root)
         self.assertEqual(record.message_ids[0].author_id, self.user_employee.partner_id)
 
         record = self.format_and_process(MAIL_TEMPLATE, self.user_employee.email_normalized, f'groups@{self.alias_domain}', subject='Email SimpleEmail')
         self.assertEqual(record.create_uid, self.user_employee)
         self.assertEqual(record.message_ids[0].subject, 'Email SimpleEmail')
-        self.assertEqual(record.message_ids[0].create_uid, self.user_employee)
+        self.assertEqual(record.message_ids[0].create_uid, self.user_root)
         self.assertEqual(record.message_ids[0].author_id, self.user_employee.partner_id)
 
     @mute_logger('odoo.addons.mail.models.mail_thread', 'odoo.models.unlink')
@@ -661,7 +717,7 @@ class TestMailgateway(MailCommon):
         record = self.format_and_process(MAIL_TEMPLATE, self.user_employee.email_formatted, f'groups@{self.alias_domain}', subject='FollowerWinner')
         self.assertEqual(record.create_uid, follower_user)
         self.assertEqual(record.message_ids[0].subject, 'FollowerWinner')
-        self.assertEqual(record.message_ids[0].create_uid, follower_user)
+        self.assertEqual(record.message_ids[0].create_uid, self.user_root)
         self.assertEqual(record.message_ids[0].author_id, follower_user.partner_id)
 
         # name order win
@@ -670,7 +726,7 @@ class TestMailgateway(MailCommon):
         record = self.format_and_process(MAIL_TEMPLATE, self.user_employee.email_formatted, f'groups@{self.alias_domain}', subject='FirstFoundWinner')
         self.assertEqual(record.create_uid, self.user_employee)
         self.assertEqual(record.message_ids[0].subject, 'FirstFoundWinner')
-        self.assertEqual(record.message_ids[0].create_uid, self.user_employee)
+        self.assertEqual(record.message_ids[0].create_uid, self.user_root)
         self.assertEqual(record.message_ids[0].author_id, self.user_employee.partner_id)
 
     # --------------------------------------------------