# Change per-user mailbox format (e.g. maildir, mdbox)

iRedMail uses `maildir` mailbox format by default, it's easy to migrate and
maintain, but if mailbox size is growing, the performance will be getting
slower due to too much disk I/O. Dovecot's own mailbox format `mdbox` has very
good performance for large mailbox due to reduced disk I/O.

You may want to switch to other mailbox format for some reason.
To help you switch easily, iRedMail-0.9.9 introduces 2 new
SQL columns (for SQL backends) and LDAP attributes (for LDAP backends) to help
you switch per-user mailbox format easily. All
[mailbox formats supported by Dovecot]https://wiki2.dovecot.org/MailboxFormat)
is supported in iRedMail.

!!! attention

    * If you're running an iRedMail release earlier than iRedMail-0.9.9, you can
      upgrade it by following [iRedMail upgrade tutorials](./iredmail.releases.html).
    * iRedAdmin-Pro RESTful API interface supports changing mailbox format too.
      Check its [API document](./iredadmin-pro.restful.api.html) (expand all
      parameters and search 'mailboxformat' or `mailboxFormat`).

!!! warning

    - Changing mailbox format does not migrate existing mailbox for you. You
      have to migrate it __BEFORE__ switching to new mailbox format, then
      update SQL/LDAP data to use new mailbox format right after migrated the
      mailbox.
    - New mailbox format will be used by Dovecot immediately after SQL/LDAP change.

## SQL backends

You can switch to different mailbox format with SQL commands below. We use
MySQL for example here.

```
USE vmail;
UPDATE mailbox SET mailboxformat='mdbox', mailboxfolder='mdbox' where username="user@your-domain.com";
```

* Value of `mailboxfolder` can be any folder name supported by Linux/BSD file
  system, but value of `mailboxformat` must be one of the formats supported by
  Dovecot, e.g. maildir, sdbox, mdbox.
* Value of `mailboxfolder` can not be same as previously used one, otherwise
  old mailbox will be messed up when Dovecot delivers new email.

## LDAP backends

You need some LDAP management tool like [phpLDAPadmin](http://phpldapadmin.sourceforge.net/),
[Apache Directory Studio](https://directory.apache.org/studio/), or command
line tool `ldapvi` (you can install it with `yum` or `apt-get` command directly)
to update mail user's LDIF data.

```
mailboxFormat: mdbox
mailboxFolder: mdbox
```

* Value of `mailboxFolder` can be any folder name supported by Linux/BSD file
  system, but value of `mailboxFormat` must be one of the formats supported by
  Dovecot, e.g. maildir, sdbox, mdbox.
* Value of `mailboxfolder` can not be same as previously used one, otherwise
  old mailbox will be messed up when Dovecot delivers new email.
* With iRedMail-0.9.9, if attribute `mailboxFormat` and `mailboxFolder` don't
  present in user LDAP object, Dovecot is configured to use `maildir` as
  default mailbox format and `Maildir` (case-sensitive) as folder name.