This documentation is for Dovecot v1.x, see wiki2 for v2.x documentation.
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If your clients have the server prefix set to something like "~/mail", this will not work unless you enable mail_full_filesystem_access in your Dovecot configuration. A better solution is to change the client settings, but this at least gives you a workaround if you want to deploy Dovecot prior to tackling your client systems.

TableOfContents

Migration to Dovecot

When migrating from one IMAP server to another, you should make sure that these are preserved:

  • Mailbox subscription list
    • User would be able to manually subscribe them again if you don't want to mess with it.
  • Message UIDs
    • If UIDs are lost, at the minimum clients' message cache gets cleaned
    • Some IMAP clients store metadata by assigning it to specific UID, if UIDs are changed these will be lost.
  • Message flags
    • Lost flags can be really annoying, you most likely want to avoid it.

Here's the more server-specific instructions:

UW-IMAP

By default UW-IMAP allows access to whole home directory, and many people have chosen to store their mails in mail/ directory. This usually means that IMAP clients have set "IMAP namespace" to "mail/", which doesn't work well with Dovecot, as Dovecot by default uses mail/ directory directly. So if IMAP namespace is kept as "mail/", Dovecot would try to access "~/mail/mail/" directory.

So, removing the prefix from IMAP clients would be the first step. Next problem is that subscribed mailboxes are listed as "mail/box" or "~/mail/box" or "~user/mail/box" in subscriptions file. You'd have to remove the mail/ directory part from all of these. The subscriptions file name is also different, UW-IMAP uses .mailboxlist while Dovecot uses .subscriptions.

If your clients have the server prefix set to something like "~/mail", this will not work unless you enable mail_full_filesystem_access in your Dovecot configuration. A better solution is to change the client settings, but this at least gives you a workaround if you want to deploy Dovecot prior to tackling your client systems.

Dovecot uses UW-IMAP compatible UID and message flag headers in mboxes, so that's not a problem.

Settings:

default_mail_env = mbox:~/mail:INBOX=/var/mail/%u
# make sure mbox_locks are the same with all software that accesses your mboxes
mbox_locks = dotlock fcntl

UW-POP3

Dovecot generates POP3 UIDs differently than UW-IMAP. You most likely want to preserve them, so currently you'll have to [http://dovecot.org/patches/pop3-uidl-uwimap.patch patch Dovecot].

Courier

Courier by default uses "INBOX." as private IMAP namespace, so it has exactly the same problems as described with UW-IMAP above.

  • Courier's courierimapsubscribed is compatible with Dovecot's .subscriptions file, just rename it and remove the "INBOX." prefixes.

  • Courier's courierimapuiddb is compatible with Dovecot's dovecot-uidlist file, just rename it.

  • Courier's message flags are compatible with Dovecot (as it's specified by Maildir specification)
  • Courier's message keywords implementation isn't Dovecot compatible and there's currently no easy way to migrate them.

Settings:

default_mail_env = maildir:~/Maildir

Cyrus

See [http://madness.at/projects/ cyrus2courier], it's Dovecot-compatible. Also mirrored at [http://dovecot.org/tools/ dovecot.org].

None: Migration (last edited 2010-11-02 22:24:58 by TimoSirainen)