We had this this morning:
Oct 25 12:36:34 msslat dovecot: imap(keh2): Error: user keh2: Initialization failed: Namespace '#mbox/': mkdir(/stage/mail/imap1/keh2/mail) failed: Permission denied (euid=2291(keh2) egid=101(luci) missing +w perm: /stage/mail/imap1, euid is not dir owner) Oct 25 12:36:34 msslat dovecot: imap(keh2): Error: Invalid user settings. Refer to server log for more information. Oct 25 12:36:35 msslat dovecot: imap-login: Login: user=<keh2>, method=PLAIN, rip=128.40.73.160, lip=128.40.73.13, mpid=26736 Oct 25 12:36:35 msslat dovecot: imap(keh2): Error: user keh2: Initialization failed: Namespace '#mbox/': mkdir(/stage/mail/imap1/keh2/mail) failed: Permission denied (euid=2291(keh2) egid=101(luci) missing +w perm: /stage/mail/imap1, euid is not dir owner) Oct 25 12:36:35 msslat dovecot: imap(keh2): Error: Invalid user settings. Refer to server log for more information.
Because the parent directory was rwxr-xr-x root.root
The problem is that for some reason dovecot then wedged and a lot of other stuff piled up behind it, causing people to complain their mail wasn't coming through. Load average climbed to over 100.
Creating the user directories freed things up...