Can mail auto-delete old mail from specific folders?

Question

I would like to have mail automatically delete mail older than one month in specific folders where I store email from mailing lists. Is there a way to get mail to do this without my having to select the messages in the folder and "apply rules"?
It seems that rules are only applied to new messages or ones you select.
Automator does not have an option to "find messages" which are "older than..." It does allow you to select messages recieved "before..." but you have to set a specific date.

Answer 1

Thanks for your help Mulder, I'll try to clarify.
The effort is indeed made here to clean up messages I've received - typical mailing list folders can grow out of control quickly without a little maintenance.
I did make some Rules, ones anchored on both the sender name and date received, with the action being to send the matched messages to the Trash, or to simply change the highlighting as a test.
It was never, and still is not, clear to me whether I must manually initiate these rules. I would hope not, however I was never able to see them work, even with the most basic of criteria, whether left to their own devices or manually selecting apply rules from the menu.
Anyways, I guess my point here is to validate my suspicion that Rules are indeed the one and only way one would accomplish this?