How to Automatically Trim Spam Mailbox in Mail

Using Apple Mail, does anyone have a suggestion for how to automatically trim the Spam mailbox when spam gets to be, say, 30 days old?

I’ve just started using Apple Mail after migrating from Eudora.
I like the way both programs do auto deletion of spam. I was able to use Eudora’s mechanism with SpamSieve, but I can’t seem to figure out how to do it with Mail.

Please see this page.

Deleting Old Spam in Entourage?
Is there a way to do the same thing in Entourage?

Yes, there is.