[Exim] filtering with virtual mailboxes

Hello

I'm using Exim4 with courier-imap / pop, and mysql to set up virutal
mailboxes for a few domains I host.

For local address', I have mail filtering enabled through .forward .. sorts
mail from various lists into appropriate folders, etc.

For virtual mailboxes, I have no idea how I can achieve the same
functionality....

Is it asking the impossible to be able to have the filter rules stored in
the DB somewhere?

Thanks for any suggestions ....

Tim