Description:

After updating the bot's avatar through the Synapse admin panel, the following occurred:

1. Postmoogle sent a greeting message ("Hello, kupo!") to an existing room with an already configured mailbox
2. Emails sent to the configured mailbox (mailname@nameserver.com) stopped arriving in the Matrix room

Steps to reproduce:

1. Have a working Postmoogle mailbox configured in a room
2. Update bot's avatar via Synapse Admin API
3. Greeting message is triggered unexpectedly
4. Incoming emails no longer delivered to the room

Expected behavior:

• Avatar update should not trigger membership events that activate the greeting flow
• Existing mailbox configuration should remain functional

Actual behavior:

• Greeting message triggered as if it's a new room
• Email delivery stopped (unclear if related or coincidental with maintenance)