Panix Help System: Should I use procmail?

As we mentioned on the intro page, you can enable SpamAssassin and virus checking without using procmail at all. But you should still use procmail if

you want to save your mail to non-IMAP folders (in old-style mbox format).
you want to forward some, but not all, of your incoming mail to another address.
you have custom Procmail recipes already defined, and want to keep them, or you want to develop custom recipes beyond what is built into SpamAssassin.
you use, or want to use, tagged addressing (i.e. user+tag@panix.com or tag@user.users.panix.com), and sort your mail by the tag.