I have the same problem with:
Bluewin Mail provided by Swisscom
Outlook Mail
iCloud Mail
For iCloud I generated an application specific password.
For all of these accounts I get a warning as described here https://community.openhab.org/t/problem-refreshing-imap-pop3/95637?u=chthsch
Does anyone have a solution for this problem?
I have enabled DEBUG mode, but do not get any additional entry in the log files.