Hello,
Short report, in case it is useful — I have posted the detail at support.stalw.art
under Feature Ideas.
Microsoft’s IMAP connector (Outlook / “new Outlook” external account sync) sends
ENABLE CONDSTORE UIDONLY immediately after login, then addresses messages by sequence
number. Stalwart answers BAD [UIDREQUIRED], exactly as RFC 9586 requires, and the
connector logs out. The session dies 794 ms after it opens and the mailbox never syncs.
Nothing is reported to the user - Outlook shows an empty folder.
This is not a bug report: the server is conformant and the client is not. But since
UIDONLY arrived in 0.16.17 and cannot be turned off, the practical effect is that no
Stalwart mailbox from that version on can be connected to Outlook.com. Microsoft’s own
advice (their Q&A 5567647) is “disable UIDONLY on your IMAP server”, which Stalwart
does not allow.
I am asking for a setting to stop advertising it - default on, so nothing changes for
anyone else. I have verified the idea works against the real connector, and there is a
26-line sketch on a fork if it helps:
(written in an AI-assisted session, which your CONTRIBUTING.md rules out for code - so
it is an illustration of the shape, not something to merge).
I have a Microsoft connector pointed at a Stalwart server with logs on both ends, so if
you produce a build I am glad to test it for you.
Thanks for Stalwart.