cat the contents of a txt attachment and paste in body of new email?

Hello all, I have what I think should be a simple problem - but I can't
find any solution. I have a Big Brother client running on an AS/400
that relays bad system messages to an email account. The problem is
that the content of the bad message is placed inside a txt attachment.
I need to be able to pull the contents of that attachment and paste
them in the body of the email. I think I may just have to send the Big
Brother message to a bogus email account, have a script parse the
email, and then email the results to a legitimate email address. Any
ideas on how to do this? Any help would be appreciated.

Thanks,
Matt