We have an interesting setup, we have two servers for email, one with SmarterMail handling inbound and outbound messages, and a file server that stores messages.
So, every user has two mailboxes, one SmarterMail inbox, and one local inbox on the file server.
We have a local in-house built email viewer and sender that reads emails from the file server and sends any outbound messages out through SmarterMail.
We want to eliminate this system and just use SmarterMail, but I have several years worth of emails that need migrated. As well as folders.
We want to make this as smooth a transition as possible and not have to have people recreate all of their folders. Plus I'm still not sure how to handle sent emails.