Bugzilla

(In reply to klaus from comment #3)
> thanks for the good explanation. 
> 
> TB is now redownloading everything (40 GB...).
> I have now set an exclusion for Kaspersky on the imapmail subfolder. Probably will have to wait for the full redownload to finish to see whether that helps. In a next step, I could also block scanning of port 143. Want to do it step by step to understand what is the origin.
> 
> For my understanding: if port scanning of 143 would strip an attachment from an email, the email on server is different from its copy in TB. Would TB know? Or would the server tell to TB at TB's next request for that imap-folder?

You have mentioned scanning on port 143.  this is in itself perhaps an issue as the imap mail is unlikely to be on an encrypted connection on that port.  Generally encrypted email travels on port 993 for IMAP.  Is the connection encrypted and on a non default port for encryption?   That might be enough to trip up the unwary, or the anti virus.