My secondary email account has not received emails since December 28th. I saw a tiny alert which advised me I had to log into the secondary account, so I did that. I've sent a test email to the account and I'm getting an "undeliverable" message 5.1.1 "not our customer". This is so irritating.
Then you need to sign into the account, and then click on "My Account" at the top of the page to check it out. A 5.1.1 error means something is wrong with the email address in question.