I am running sendmail on a Slackware 10.1 machine. We send out listserve messages to our employees many do not use their corporate account for some reason or another. The listserve message comes from a non-existent user, for the sake of discussion called userq.
However when userq sends a message some ISP's block it because it is an invalid user. We used to have a userq, but this allowed people to respond and everyone was flooded with responses to emails they did not want, we were using petidomo at that time.

Can I set up a user, so if someone verifies that user, it will come back valid, but I do not want that user to be able to receive emails.

Is it possible to set up the user but alias everything to a non-existent account?