[Exim] Hi.. moving to vitrual domains..

I am moving from having a couple of domains that were both writing to
the same spool (at the time the userbase was small enought that there
was not issues with the same user name) to different spools...
Any suggestions as to how to moving my current mailboxes (/var/mail) to
/var/mail/domain
Any caveats?

Has anyone had a look at :
http://www.ex-parrot.com/~chris/vmail-sql/

Any thoughts on it?

Derrick