Thanks.
Unfortunately,
* I'm already authenticating and getting this problem
* I'm getting this problem on more than 1 accounts, and this is new as of 24 hours ago. So highly unlikely to be a change in settings on the mail server end (my work email AND a separate personal email)
* It's a problem I've had on some hotel connections, now I'm getting it at home, so I assume it's something with my home connection (Verizon), but I'm not expert