[Dovecot] mbox sync: UID inserted in the middle of mailbox...

[Simon Bowden]

Hi,

We're getting a lot of errors like this:
Mar  7 10:02:35 imapserver dovecot: imap(user1): mbox sync: UID inserted in the middle of mailbox /home/user1/mail/mail/INBOX.Trash (8 > 2, seq=2,idx_msgs=6)

We have several hundred people using the server, and at least 22 have had 
this error in the past 24 hours. The numbers at the end change between 
each user, which I guess you'd expect.

I was able to make the errors go away for one user by removing the index 
files (rm -rf ~/mail/.imap/INBOX), so I'm guessing they were corrupt. 
However, the problem with this is that:
  1) It requires user intervention
  2) The symptom is that they aren't seeing any new mail in the affected
     mailbox.

I had thought that the indexing stuff would not *give up*, but would 
reindex a directory if there was a problem.

Anyone able to help?

Some info on our setup:
/home/user is nfs-mounted.

We allow them to configure their mbox/maildir type and location, but 
obviously this is only relating to mbox ones.

Here's the config file, stripped of comments and blank lines:

====================
protocols = imap imaps
ssl_cert_file = /etc/ssl/certs/imapd.cert
ssl_key_file = /etc/ssl/private/imapd.pem
ssl_ca_file = /etc/ssl/certs/cacert.pem
log_timestamp = "%Y-%m-%d %H:%M:%S "
login_processes_count = 6
first_valid_uid = 40
mail_extra_groups =
default_mail_env = mbox:~/mail/:INBOX=~/.incoming-mail
mmap_disable = yes
mail_drop_priv_before_exec = yes
protocol imap {
   mail_executable = /usr/local/mail/imap-wrapper
   imap_client_workarounds = outlook-idle delay-newmail tb-extra-mailbox-sep
}
protocol pop3 {
}
auth default {
   mechanisms = plain gssapi
   passdb pam {
     args = session=yes *
   }
   userdb passwd {
   }
   user = root
}
plugin {
}
====================

/usr/local/mail/imap-wrapper is just a script that lets them configure the 
setup a bit (effectively change value of MAIL, and some namespace stuff), 
ultimately running /usr/lib/dovecot/imap.

The nfs mount options on the home directory mount are:
rw,hard,intr,rsize=8192,wsize=8192,nosuid,nodev,vers=3,proto=udp


Thanks!

Cheers,

  - Simon