Sender receives message that our email addresses don't exist
Sender with a suddenlink.net address receives "Mail System Error - Returned Mail" messages when she sends an email to any of our three comcast addresses. Each time it says that the email address "does not exist" yet it is correctly typed and included in the "Mail Administrator" notice she receives. The addresses are all ones we've had for years.
Emails from two different senders are now going to our junk mail. Until 2-3 weeks ago they always came to our inboxes with no problem.
I hope you can help! Both of these situations are very frustrating