In my setup, I put mail indices outside the user's mailbox locations (user mailboxs are NFS, indices stored local attached storage).

I notice that sometimes, there are 2 sets of indices representing the same mailbox: one at top level, one underneath .imap/. (They usually appear in the latter.) For example, if I have the configuration

(Dovcot version 3.2.21)
mail_location = mbox:~/mail:INBOX=/nfs/mail/%n:INDEX=/cache/%n

I see for a particular user

[1] drwx------   5 user     group      512 Feb 22 21:56 /cache/user/box
[2] drwxr-xr-x   5 user     group      512 Feb 22 21:46 /cache/user/.imap/box

cooresponding to their mailbox in ~user/mail/box. Each of these have the dovecot.* index files.

If I delete [1], it comes back. The timestamps are close to each other so both sets are being used, possibly by different clients.

Another quirky discovery is 2 /.imap/ folders beneath each other e.g.

/cache/user/.imap/folder1/folder2/.imap/box/dovecot.index

What determines which index pathname gets created or used?

Joseph Tam <jtam.home@gmail.com>