Same problem here when trying to set up smtp relay for outbound email channel. I used the docker-compose set up.
Hello again,
it seems that this problem occurs when some batch processing of tickets or a batch of some timed tickets are opened synchronously.
We just investigated that there are message rate limits with microsoft exchange:
Message rate limits and throttling | Microsoft Docs
Maybe it is somehow possible to let batches of tickets to be processed with some time delay?
Best regards
Okay i´ve found out that my SMTP relay does not used SSL/TLS and there is no option to disable the usage of SSL/TLS in the email channels settings.