I am currently running wu-imap on the company imap server. I am considering switching to courier so we can use maildirs because parsing all of those mailboxes has maxed out our cpu's. The main problem I am having is figuring out how to get courier-imap to read maildirs in other places such as in the home directory itself. I have read the RFC and IMAP namespaces don't make any sense to me. Using mutt I can change to {mail}inbox or {mail}inbox.foo but I can't change to a mailbox in the home directory. There appears to be a shared namespace in the RFC also but I am not sure how to make use of that or what it does.

Also, does anyone have any migration strategies or scripts? If we do decide to go for it I am going to have to convert around 40G of mbox files into Maildirs, preferably in place so we don't confuse the users by moving stuff around on them. Writing a script to search over all of /home looking for stuff that looks like mbox files and automatically converting them sounds kinda risky. We've got good backups but the real problem is the length of the downtime. Converting 40G on this machine will take 16 hours best-case. It would be nice if we could do it a little at a time but courier only does Maildir (how inconvenient) and obviously only one daemon can listen on 143.