Your question
Hello, the account was setup correctly in outlook, and it seems it logs in to the account. but no emails are shown. In Thunderbird and Bulwark Webmail everything is fine. What could be the reason?
The thing to check first is where the connections are actually coming from. New Outlook does not talk IMAP from the desktop: Microsoft’s cloud sync service connects to your server on the user’s behalf, from Microsoft IP ranges. So the account setup succeeding tells you the credentials are fine, but the sync itself is a different client from a different address, which is why Thunderbird from your own machine is unaffected.
Have a look at Security > Blocked IPs and filter for Microsoft ranges. If any are there, add them under Allowed IPs; the allowlist overrides the blocklist. This bites people often enough that it is worth ruling out before digging into IMAP itself.
If that is clear, could you send the IMAP telemetry for one Outlook sync session, specifically whether it gets as far as SELECT INBOX and what the FETCH and SEARCH responses look like? Also useful: your server version, whether the folder tree shows up with an empty Inbox or nothing appears at all, and whether maxConcurrent, maxRequestRate, maxMessagesPerCommand or maxMessagesPerSave have been changed from their defaults.
Hello,
how do I know which ranges are from microsoft?
there are quite a lot blocked ip adresses there…
actually over 1500.
I saw now the ms ip, it is not blocked.
How do I get the whole Imap telemetry?
The Folder Tree does not show up.
Server is 0.16.18.