On Sun, 2010-08-08 at 17:40 +0200, Yves Goergen wrote:

Hello,

the migration guide from Courier-IMAP to Dovecot says that I should change the folders namespace to "INBOX." if I want a seamless migration.

Yes.

Isn't it that e-mail clients determine that namespace automatically? At least I never needed to enter one in Thunderbird and then it was there.

You can of course try what happens, but not all clients have automatic namespace configuration, and also some TB users also could have manually explicitly overridden it.

What happens if I copy the database, all the Maildir files, run the migration script to convert the special files and don't change that namespace - will clients show an error message and stop working or will it still work?

Probably the worst that can happen is that clients will show only INBOX and users are panicking over what happened to their other mailboxes until they change the configuration.

Alternatively you can create a hidden namespace with prefix=INBOX. that such users would use. That should also be pretty much transparent for most users. http://wiki.dovecot.org/Namespaces -> Backwards Compatibility: Courier IMAP