This documentation is for Dovecot v2.x, see wiki1 for v1.x documentation.

Maildir configuration

See ["MailboxFormat/Maildir"] for a complete description of how Dovecot has implemented Maildir support.

Mail location

Maildir exists almost always in ~/Maildir directory. The mail location is specified with:

mail_location = maildir:~/Maildir

Control files

Dovecot stores some Maildir metadata into two control files:

Both of these files are described fully in ["MailboxFormat/Maildir"]. The important thing to remember about them however is that they shouldn't be treated the same way as index files. Index files can be deleted and rebuilt without any side effects, but if you delete control files you'll cause messages to get new UIDs and possibly lose keyword names.

If the messages get new UIDs, the IMAP clients will invalidate their local cache and download the messages all over again. If you do this for all the users, you could cause huge disk I/O bursts to your server.

Dovecot can't currently handle not being able to write the control files, so it will cause problems with [:Quota/FS:filesystem quota]. To avoid problems with this, you should place control files into a partition where quota isn't checked. You can specify this by adding :CONTROL=<path> to mail_location, for example:

mail_location = maildir:~/Maildir:CONTROL=/var/no-quota/%u

Index files

In some situations you may wish to not keep the index files in the user's home folder, for instance when ~/Maildir is attached via NFS. You can specify this by adding :INDEX=<path> to mail_location, for example:

mail_location = maildir:~/Maildir:INDEX=/var/spool/dovecot/%u

The user's home folder will be created dynamically at runtime by Dovecot, as well as the folders necessary for each set of indexes in that user's mail tree.

NOTE: ensure that the parent level folder, /var/spool/dovecot/ e.g., has the proper writable permissions for your dovecot installation.

Optimizations

Filesystem optimizations

See "Maildir and filesystems" section in ["MailboxFormat/Maildir"].