* The new IMAP and POP3 server will be a virtual server.
* The IMAP/POP3 see will be separated from the SMTP servers so the IMAP performance won't suffer from spam attacks as much anymore.
* We are migrating from [UW IMAP/POP3](http://www.washington.edu/imap/) to [Dovecot](http://www.dovecot.org/).
* We are migrating from the uncommon, fragile and UW-IMAP-only [MBX mailbox format](http://wiki.dovecot.org/MailboxFormat/mbx) to the established [[Maildir mailbox format|http://en.wikipedia.org/wiki/Maildir]].
* The Maildir mailbox format stores each mail in its own file.
* A Maildir mailbox is a directory with a defined set of subdirectories on disk.
* No more 2GB size limit per mailbox.
* Faster backup.
Path Changes
------------
If you have a manually edited `.procmailrc` or `.forward` (deprecated), or use scripts which access your IMAP mailboxes on disk, the following paths must be changed after the migration:
### /var/mail
*`/var/mail/$USER` is no longer used
* Therefore, `/var/mail` is no longer exported via NFS.
* E-mail clients which access the incoming e-mail via `/var/mail` (e.g. (X)Emacs' RMAIL) are no longer supported.
### New INBOX Path on disk
* New mail gets delivered to `/var/imap/$U/$USER/new/` where `/var/imap/$U/$USER/` is the Maildir format mailbox visible as `INBOX` in the IMAP client.
*`/var/imap/$U/$USER/INBOX` is now `/var/imap/$U/$USER/` which is a Maildir format mailbox visible as `INBOX` (as before) in the IMAP client.
### Conversion to Maildir
* The conversion is done by us during the migration.
* Mailboxes in the following format will be converted: MBX, mbox (classical Unix™ mailbox), compressed mbox, Maildir
* The new IMAP server supports mail folders inside mail folders. You may need to change you mail clients settings to be able to use this feature.
* The IMAP directory separator on disk is a dot.
* Therefore the names of folders on disk under the directory `/var/imap/$U/$USER/` have changed.
* The folder name is prepended by a dot (".") on disk.
* Slashes ("/") have been replaced by dots (".").
* Dots in the original folder name have been replaced by underscores.
Example:
```
Old MBX or mbox file: /var/imap/$U/$USER/Mailinglists/Announcements/Example.org
New Maildir directory: /var/imap/$U/$USER/.Mailinglists.Announcements.Example_org/
```
### Changes to other files
*`/home/$USER/.mailboxlist` moves to `/var/imap/$U/$USER/subscription` and will be converted by us.
*`.procmailrc`: We will adapt all path names in the approximately two dozens `.procmailrc`s manually. We recommend you to check the modified `.procmailrc` if it works as before.
