Apologies for the formatting. Retrying with HTML formatting disabled:
We are getting the same warnings on 2 separate test servers; one with local ZFS storage, the other one with NFS storage (single server, data not shared with any other servers). We are imapsync'ing a few hundred user accounts from the production server so there is a lot of emails transfer a day. The warnings occur at random times and with random users.
I reinstalled 2.3.21 from source (originally was using Dovecot repo packages) and tested by reverting that commit. The warnings continued.
Next I tried with Dovecot 2.3.20 and still got the same warnings after a while.
# 2.3.20 (80a5ac675d): /usr/local/etc/dovecot/dovecot.conf # Pigeonhole version 0.5.20 (149edcf2) # OS: Linux 5.4.0-171-generic x86_64 Ubuntu 20.04.6 LTS nfs4
Feb 13 15:38:25 dovecot: imap-login: Login: user=<username>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=272469, TLS, session=<t+48YEkRrrN/AAAB> Feb 13 15:38:27 dovecot: imap(username)<272469><t+48YEkRrrN/AAAB>: Warning: mdbox /mail/spool/username/storage: Inconsistency in map index (3,40 != 3,56) Feb 13 15:38:27 dovecot: imap(username)<272469><t+48YEkRrrN/AAAB>: Warning: fscking index file /mail/spool/username/storage/dovecot.map.index Feb 13 15:38:27 dovecot: imap(username)<272469><t+48YEkRrrN/AAAB>: Warning: mdbox /mail/spool/username/storage: rebuilding indexes Feb 13 15:38:29 dovecot: imap(username)<272469><t+48YEkRrrN/AAAB>: Error: Mailbox INBOX: /mail/spool/username/mailboxes/INBOX/dbox-Mails/dovecot.index reset, view is now inconsistent Feb 13 15:38:29 dovecot: imap(username)<272469><t+48YEkRrrN/AAAB>: Warning: fscking index file /mail/spool/username/storage/dovecot.map.index
I will try with an even older version to continue testing...