On 2 Nov 2018, at 20.58, Poliman - Serwis <serwis@poliman.pl> wrote:

I have a problem for specific mailbox. In mail.err file I see a lot:

Nov  2 07:41:17 s1 dovecot: imap(artur@example.pl): Error: unlink(/var/vmail/example.pl/artur/Maildir/dovecot.index.cache) failed: No such file or directory (in mail-cache.c:28)
Nov  2 07:41:17 s1 dovecot: imap(artur@example.pl): Error: Corrupted index cache file /var/vmail/example.pl/artur/Maildir/dovecot.index.cache: Broken MIME parts for mail UID 2356 in mailbox INBOX: Cached MIME parts don't match message during parsing: Cached header size mismatch (parts=)
Nov  2 07:41:19 s1 dovecot: imap(artur@example.pl): Error: unlink(/var/vmail/example.pl/artur/Maildir/dovecot.index.cache) failed: No such file or directory (in mail-cache.c:28)
Nov  2 07:41:19 s1 dovecot: imap(artur@example.pl): Error: Corrupted index cache file /var/vmail/example.pl/artur/Maildir/dovecot.index.cache: Broken MIME parts for mail UID 2431 in mailbox INBOX: Cached MIME parts don't match message during parsing: Cached header size mismatch (parts=)
Nov  2 07:41:21 s1 dovecot: imap(artur@example.pl): Error: unlink(/var/vmail/example.pl/artur/Maildir/dovecot.index.cache) failed: No such file or directory (in mail-cache.c:28)
Nov  2 07:41:21 s1 dovecot: imap(artur@example.pl): Error: Corrupted index cache file /var/vmail/example.pl/artur/Maildir/dovecot.index.cache: Broken MIME parts for mail UID 2552 in mailbox INBOX: Cached MIME parts don't match message during parsing: Cached header size mismatch (parts=)
Nov  2 07:41:21 s1 dovecot: imap(artur@example.pl): Error: unlink(/var/vmail/example.pl/artur/Maildir/dovecot.index.cache) failed: No such file or directory (in mail-cache.c:28)
Nov  2 07:41:21 s1 dovecot: imap(artur@example.pl): Error: Corrupted index cache file /var/vmail/example.pl/artur/Maildir/dovecot.index.cache: Broken MIME parts for mail UID 2605 in mailbox INBOX: Cached MIME parts don't match message during parsing: Cached header size mismatch (parts=)
Nov  2 07:41:24 s1 dovecot: imap(artur@example.pl): Error: unlink(/var/vmail/example.pl/artur/Maildir/dovecot.index.cache) failed: No such file or directory (in mail-cache.c:28)
Nov  2 07:41:24 s1 dovecot: imap(artur@example.pl): Error: Corrupted index cache file /var/vmail/example.pl/artur/Maildir/dovecot.index.cache: Broken MIME parts for mail UID 2717 in mailbox INBOX: Cached MIME parts don't match message during parsing: Cached header size mismatch (parts=)

I have many mailboxes on the server and each of them work perfectly except this one.

Somehow cache files have been corrupted.

You can try to fix them with: doveadm force-resync -u user INBOX

Sami