Fix email error, comcast.net vs. comcast.com?

Question

A friend sends email with the address of [e-mail]. Replies to it will generate an error message like 'no such mailbox.' The actual email address for sending is [e-mail].

Why is does his sending name come up .com and his receiving name has to be .net, and how can he fix it?

(I have comcast, which uses comcast.net, and have never had this problem.)

Answer 1

He needs to go to the options for that mailbox and just change any option that say comcast.com to comcast.net. Comcast.com doesn't exist for mail so he probably put it in accidently when he set up his mailbox.