Some customers are experiencing problems with IMAP/POP access and we are investigating this. We will update this post when we know more. Sorry for the inconvenience this is causing.
UPDATE 12:15 CET: We are continuing investigations and restarting various services in order to fully restore access and stabilize the situation.
UPDATE 07.02.2022 18:30 CET: The underlying cause was related to a deployment of database logging of authentication attempts a few days earlier that caused increasing delays in responses to authentication requests. This deployment has been rolled back and the IMAP/POP related access issues were then resolved.