Appwrite not sending Emails

I’m running a self-hosted Appwrite instance (v1.8.1) and I can’t get invite emails to send when using the team invite flow described in the docs: https://appwrite.io/docs/products/auth/team-invites

My mail server is Mailcow (v2025-12a).

Sending emails manually works fine: if I create and send messages via an Appwrite Function using the Messaging service, the emails are delivered without any issues. However, anything Appwrite is supposed to send on its own (like user/team invite emails) never gets sent.

SMTP is configured and enabled in Appwrite and uses the same credentials as the working Messaging setup.

When Appwrite should send an invite email:

nothing shows up in the Appwrite Docker logs (except a warning about no SMS provider)

nothing shows up in the Mailcow logs either

When emails are sent via the Messaging service, I do see them in the Mailcow logs.

So it looks like Appwrite never even tries to send invite emails, even though SMTP itself is working.