Remove pushers when deleting 3pid from account

CHANGES.md

@@ -1,3 +1,5 @@
+Users will stop receiving message updates via email for addresses that were once, but not still, linked to their account
+
 Synapse 1.41.0rc1 (2021-08-18)
 ==============================
 

changelog.d/10581.bugfix

@@ -1 +1 @@
-Remove pushers when deleting 3pid from account.
+Remove pushers when deleting 3pid from account. Pushers for old unlinked emails will also be deleted.

docs/upgrade.md

@@ -107,6 +107,11 @@ This may affect you if you make use of custom HTML templates for the
 The template is now provided an `error` variable if the authentication
 process failed. See the default templates linked above for an example.
 
+# Upgrading to v1.42.0
+
+## Removal of out-of-date email pushers
+Users will stop receiving message updates via email for addresses that were
+once, but not still, linked to their account.
 
 # Upgrading to v1.41.0
 

synapse/storage/databases/main/pusher.py

@@ -396,42 +396,57 @@ def _delete_pushers(txn) -> int:
     async def _remove_deleted_email_pushers(
         self, progress: dict, batch_size: int
     ) -> int:
-        """A background update that deletes all pushers for email addresses no longer
-        associated with a user.
+        """A background update that deletes all pushers for deleted email addresses.
+
+        In previous versions of synapse, when users deleted their email address, it didn't
+        also delete all the pushers for that email address. This background update removes
+        those to prevent unwanted emails
+
+        Args:
+            progress: dict used to store progress of this background update
+            batch_size: the maximum number of rows to retrieve in a single select query
+
+        Returns:
+            The number of deleted rows
         """
 
         last_pusher = progress.get("last_pusher", 0)
 
         def _delete_pushers(txn) -> int:
 
             sql = """
-                SELECT p.id, p.user_name, p.add_id, p.pushkey
+                SELECT p.id, p.user_name, p.app_id, p.pushkey
                 FROM pushers AS p
-                    JOIN user_threepids AS t ON t.user_id=p.user_name
-                WHERE p.app_id = 'm.email'
-                    AND t.medium = 'email'
-                    AND t.address = p.pushkey
+                    LEFT JOIN user_threepids AS t
+                        ON t.user_id=p.user_name
+                        AND t.medium = 'email'
+                        AND t.address = p.pushkey
+                WHERE t.user_id is NULL
+                    AND p.app_id = 'm.email'
                     AND p.id > ?
                 ORDER BY p.id ASC
                 LIMIT ?
             """
 
             txn.execute(sql, (last_pusher, batch_size))
-            ids = [row[0] for row in txn]
 
+            last = None
+            num_deleted = 0
             for row in txn:
+                last = row[0]
+                num_deleted += 1
                 self.db_pool.simple_delete_txn(
                     txn,
                     "pushers",
                     {"user_name": row[1], "app_id": row[2], "pushkey": row[3]},
                 )
 
-            if ids:
+            if last is not None:
                 self.db_pool.updates._background_update_progress_txn(
-                    txn, "remove_deleted_email_pushers", {"last_pusher": ids[-1]}
+                    txn, "remove_deleted_email_pushers", {"last_pusher": last}
                 )
 
-            return len(ids)
+            return num_deleted
 
         number_deleted = await self.db_pool.runInteraction(
             "_remove_deleted_email_pushers", _delete_pushers

synapse/storage/schema/main/delta/63/02delete_unlinked_email_pushers.sql

@@ -0,0 +1,20 @@
+/* Copyright 2021 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+-- We may not have deleted all pushers for emails that are no longer linked
+-- to an account, so we set up a background job to delete them.
+INSERT INTO background_updates (ordering, update_name, progress_json) VALUES
+  (6302, 'remove_deleted_email_pushers', '{}');