I've tested this only with a test user.

http://dovecot.org/tools/courier-dovecot-migrate.pl

http://wiki.dovecot.org/Migration/Courier

Migrate Courier IMAP (any version) and Courier POP3 (v0.43+) to

Dovecot v1.0

by Timo Sirainen. This is public domain.

Usage: [--quiet] [--convert] [--overwrite] [--recursive] [<conversion

path>]

--quiet: Print only errors

--convert: Do the actual conversion. Without this it only shows if

it works.

--overwrite: Ovewrite dovecot-uidlist file even if it exists

already.

--recursive: Recursively find maildirs to convert

<conversion path>: Maildir directory, or with --recursive its parent

directory or its parent's parent

- If courierpop3dsizelist is found, it makes its best effort to keep

the

POP3 UIDLs, unless the file is more than 30 days older than

courierimapuiddb (user probably stopped using POP3).

- If courierpop3dsizelist isn't found (or it's old), the

dovecot-uidlist

is directly converted keeping all the UIDs.

- Keywords are converted from courierimapkeywords/ to maildir

filename

flags and dovecot-keywords file

- Subscriptions from courierimapsubscribed are added to Dovecot's

subscriptions file