[Dovecot] different locations for different reals

Hi

I've been reading a lot, but I think I'am confused about namespaces.

We are planning a migration of our pshychical mail storage. This will mean that subfolders are moving from /home to /var/spool/mail. I was thinking, for the migrations of creating a realm. I would like that if a user logs in with his username, the old location is used, if the user logs in with username@REALM, the subfolders are to be searched in the new location, is this possible? Can I use a different mail location per realm?

thx in advance Arne