Hi,

I'm using Akonadi with Postgres as a backend (but the very same issue occured
with Postgres). It turns out that after some time Kmail email client display
hangs when clicking on an e-mail with "getting the folder content" and not
displaying the e-mail. Sometimes after waiting several minutes the email ends
up displaying. I have disabled email content indexing, but I have several
dozens of thousands of emails.

This happens especially when Kmail has been idling for several hours.

Workarounds :
- Restarting Akonadi server fixes the issue.
- Otherwise wait several minutes.

The issue did not appear with Bullseye, same configuration (A POP3 mail
account, several IMAP account including one connected to Protonmail)

Looks like it happens when the IMAP connection to Yahoo mail is stuck - which
is quite often. Connection status is set to "established connection" only for
Yahoo Mail, for the other accounts (Protonmail, GMail) no issue.

Basically we should not be blocked this way.