"Password required for..." repeatedly appearing

Starting 2-3 days ago, this pop-up appears repeatedly for 2 of the 4 accounts I have added (one @outlook & one @live).

I found a few threads like this on the forums but none that I could see actually had any solutions. One mentioned checking the security linked up with the ports but I double checked and they’re all fine.

What do I do?

Have you tried removing the IMAP accounts and re-adding them?
Be sure to do an eMC backup prior (MENU > BACKUP).