We have a contact who, from a mistake, had the email address of our automated marketing system as their email. It was noreply@domain.com. So any emails coming to a queue, were made to look like they were coming from the contact.

We quickly removed the email address, however, emails are still being added to as being from the contact. I'm guessing that it's cached somewhere along the line, but I can't figure out where from.

How can we make it so the emails don't appear to come from this person?