One nice feature about Mail::Box is that it tries to make things as consistent as possible across backends. So, for example, $message->label( 'seen' ) is the same whether you're using Maildirs or IMAP, even though the way the two signal seen vs. unseen messages is very different. Shifting my example above to an IMAP routine instead of a Maildir routine probably only requires changing the way in which you call $manager->open( ... ) to include the right parameters for an IMAP type folder (server, user, password, etc.). (Assuming everything else is supported in the new type of folder, of course.)