On 7 Sep 2017, at 17.42, Ralf Becker <rb@egroupware.org> wrote:
Dovecot 2.2.31 with mailboxes in mdbox format.
Since a couple of days some mailboxes have the problem, that sieve rules moving mails to folders stop working and .sieve.log in mailbox shows:
sieve: info: started log at Sep 07 13:57:17. error: msgid=<20170907155704.EGroupware.S4yThVJRr12WSiJLpKbK0Bz@somedomain.egroupware.de>: failed to store into mailbox 'INBOX/Munser': Mailbox doesn't exist: INBOX/Munser.
When I do a doveadm mailbox list -s -u <user>@<domain> I get all folders incl. the one mentioned above, while doveadm mailbox list without -s shows just user INBOX
Subscriptions are stored independently from the actual folders. So it looks like the subscription file exists and is correct, but somehow you've lost all the folders. Do you see the folders in the filesystem under user/mailboxes/ directory? My guess is that it only has INBOX, which means the folders were deleted by something (Dovecot corruption can't lose entire folders - something must explicitly delete them).