Dovecot: “Ambiguous mail location setting…”

My ever-present ongoing project with etherknet.com is to develop a virtual hosting platform. One part of that uses dovecot as the LDA, backed by LDAP (which contains all the virtual-hosted sites, including people, roles, DNS, etc). Today I added my wife’s new domain to my server, then I began to see the following error messages in /var/log/mail.err:

dovecot: IMAP(nerida [AT] mygreenme.com.au): Ambiguous mail location setting, don't know what to do with it: /var/spool/vmail/mygreenme.com.au/nerida/ (try prefixing it with mbox: or maildir:)
dovecot: IMAP(nerida [AT] mygreenme.com.au): Mail storage creation failed with mail_location: /var/spool/vmail/mygreenme.com.au/nerida/

Curiously, this has never occurred before, even though I provide virtual hosting services for other domains in the same manner.

Not to worry…

The fix requires finding the dovecot query that produces the mail= value and prefixing it with the desired mail format. I prefer maildir:. So, in my case, that involved editing /etc/dovecot/dovecot.conf and changing from:

  userdb static {
    args = uid=vmail gid=vmail home=/var/spool/vmail/%d/%n/ mail=/var/spool/vmail/%d/%n/
  }

to:

  userdb static {
    args = uid=vmail gid=vmail home=/var/spool/vmail/%d/%n/ mail=maildir:/var/spool/vmail/%d/%n/
  }

Simple.

Oh, also, in the logs above I changed the “@” symbols to ” [AT] ” … my wife would never let me live it down if I primed her new mail account with spam.