Extracting envelope to

Is there any way to extract the envelope TO as opposed to the header TO: using 
procmail or formail?

I have procmail running as a system wide mail filter and based on the intended
recipient I'd like to do some specific filtering, but the header To: or cc:
fields may not contain the local recipient, but rather a mailing list name or
multiple recipients.

Is there some way to find the actual local recipient of this message?

        geoff