IMAP seemed to stop working

Did you try this procedure?

Maybe try to install from new beta ISO?

EDIT:

Tested it on NS 7.5 with LDAP, mailserver and roundcube:

  • updated packages in Software Center “unlocked” mode
  • now I can’t login to roundcube and see this in /var/log/imap:
    Error: Couldn't load required plugin /usr/lib64/dovecot/lib90_antispam_plugin.so: Module is for different ABI version 2.2.ABIv10(2.2.10) (we have 2.2.ABIv36(2.2.36))
  • updated to Neth 7.6 via Software Center as described here and now I can login to roundcube again and there’s no error in /var/log/imap anymore