mail stopped loading content, headers ok, over 100% CPU
I read my iCloud email from the mail app which suddenly took over 100%CPU time. My iMac does not seemingly slowed down, but mail does not load new mail content. I just can see the headers. This lasted over 2 days now...
I run mail as well on a MacBook Pro without troubles. The problem is only with my iMac.
I tried en/disabling my account. No difference.
Any idea?
iMac 2013, Catalina 10.15.7
iMac 27″, macOS 10.15