Emails sent to me from 2 people bounce back as other email address not deliverable

This happens to the same two people every time they send me an email. Neither of them have cox internet, and I have cox, but not the email address that keeps bouncing back to them. They type in my email address, but it bounces back a different address as un deliverable. I have talked to cox techs and they said they were going to fix it, but that was months ago. Any ideas? all the settings that I can manage are correct, the email address that keeps bouncing back is not in my account.