How to delete many e-mails?

        Hi,

        I had sent the following e-mail to gnu.emacs.help but I did
not get any reply to that so I thought this list might be more
suitable. 


        I use procmail to filter my e-mails to different folders and
use RMAIL to read them. Occasionally some of these folders become very
large and I wonder if there is a simple way to delete for example all
e-mails which have been sent before a specific date. Thanks in
advance.

Regards, Nader Tajvidi