I just switched from an old mail server running on an old Mac mini to a new Mac mini (2023).
The old mail server uses the same sort of software as the new one, dovecot, postfix, fetchmail, etc.
When using the old one, Thunderbird would occasionally require quite a lot of time to successfully log in, as if it had used a bunch of retries and was now waiting a minute or two for the next retry. But I thought it was just having trouble logging into the old Mac mini.
I see the same behavior between Thunderbird and the new mail server hardware with up-to-date mail suite, including dovecot. And the new machine is dedicated to the mail server software.
I've closed TBird several times while this happens, to reopen it and continue to require a long time to log in.
It's not all the time; once it logs in I can read a series of messages pretty quickly.
Does anyone else have the problem while using this combination of software?