Enable email notifications for <Mailaddress>" not persistent in Element-Web/Desktop

### Description

The Notification-Setting "Enable email notifications for < Mailaddress >" in the Element-Web/Desktop-Client isn´t persistent across logout.

### Steps to reproduce

1. Enable the Notification-Setting "Enable email notifications for < Mailaddress >" in the Element-Web-Client.

2. Log out
3. Log in
4. The Notification-Setting "Enable email notifications for < Mailaddress >" is disabled in the Element-Web-Client.

This setting isn´t persistent across logout-processes - but the Element-Desktop-Client v11.1.87 doesn´t cleared the setting.

In the log of the synapse you can see following:
**Enabled the Mailnotification:**
`2025-01-28 15:01:23,552 - synapse.push.pusherpool - 424 - INFO - POST-144318 - Starting pusher @USERNAME:matrix.XXX.at / m.email:stefan.XXX@XXX.at`

**Logout:**
`2025-01-29 07:16:30,475 - synapse.push.pusherpool - 248 - INFO - POST-1405022 - Removing pusher for app id m.email, pushkey stefan.XXX@XXX.at, user @USERNAME:matrix.XXX.at 2025-01-29 07:16:30,479 - synapse.util.task_scheduler - 383 - INFO - task-delete_device_messages-16-hVmSQovSBELZmDnB - Task complete: 0.003sec (0.000sec, 0.000sec) (0.000sec/0.002sec/2) [0 dbevts] 'ILJDAUULFV', {'user_id': '@USERNAME:matrix.XXX.at', 'device_id': 'ILJDAUULFV', 'up_to_stream_id': 189}`

IMHO this doesn´t make sense - this setting should be persistent or there should be an config-entry where the admin could decide if he want´s that the setting get´s cleared.

### Homeserver

matrix.org and my own homeserver

### Synapse Version

1.123.0

### Installation Method

Other (please mention below)

### Database

PostgreSQL - single PostgreSQL server - not ported - no restore

### Workers

Single process

### Platform

OpenShift

### Configuration

_No response_

### Relevant log output

```shell
**Enabled the Mailnotification:**
2025-01-28 15:01:23,552 - synapse.push.pusherpool - 424 - INFO - POST-144318 - Starting pusher @USERNAME:matrix.XXX.at / m.email:stefan.XXX@XXX.at

**Logout:**
2025-01-29 07:16:30,475 - synapse.push.pusherpool - 248 - INFO - POST-1405022 - Removing pusher for app id m.email, pushkey stefan.XXX@XXX.at, user @USERNAME:matrix.XXX.at 2025-01-29 07:16:30,479 - synapse.util.task_scheduler - 383 - INFO - task-delete_device_messages-16-hVmSQovSBELZmDnB - Task complete: 0.003sec (0.000sec, 0.000sec) (0.000sec/0.002sec/2) [0 dbevts] 'ILJDAUULFV', {'user_id': '@USERNAME:matrix.XXX.at', 'device_id': 'ILJDAUULFV', 'up_to_stream_id': 189}
```

### Anything else that would be useful to know?

Also discussed on https://app.element.io/#/room/#synapse:matrix.org and https://github.com/element-hq/element-web/issues/29117