Bad Return addresses.

In recent months, Netcom has allowed its Netcruiser customers to retrieve
mail from an address that looks like this:

        user(_at_)popd(_dot_)netcruiser

The recent customers of this service have started to use this as their
return address (which doesn't work).  An unfortunate side-effect of this
is that whenever one of these uninformed people try to request something
from me - my inbox gets filled with bounced mail.

I would like to do two things with this mail.

The first is to have procmail respond to any mail from
user(_at_)popd(_dot_)netcruiser at user(_at_)ix(_dot_)netcom(_dot_)com(_dot_)  
The other thing I would like
to do is correct the bad address and pass the message along to the rest of
my rc's for proper filtering.

I am assuming that this will handle the first part (but am not really
sure):

:0 
* ^From:.*popd.netcruiser
{
IXEN=`$FORMAIL -zrx To:| sed -e 's/@.*//'`

        :0
        |($FORMAIL -r -I"To: $IXEN(_at_)ix(_dot_)netcom(_dot_)com"\
                -I"From: Wotan's Auto-Responder <wotan(_at_)netcom(_dot_)com>"\
                -A"Precedence: junk"                            \
                -A"X-Loop: $LOOP"                               \
                -I"Subject: Your From line needs to be fixed";  \
                cat $PMDIR/instruct )                            \
             | $SENDMAIL -oi -t
}

With instruct being a polite message explaining the problem with their
address and how to fix it.

Now is it possible to have formail correct the bad from address and pass
the message on to the rest of my filters?

Or would I be better off telling the Netcruiser that their mail can not be
processed by me due to the bad from line, and that they should resend
after making the correction?