Mail server is not working

[Saaish]

I've verified that the email account username and password are correct by logging into the account via outlook365, and verified that it's receiving mail.  When I configure the incoming mail server identically to 2 other existing incoming mail servers that work fine (secure imap, correct ports, host name, etc. ), I still get an "AuthenticationFailedException: AUTHENTICATE failed." error.  I've tried switching to POP, but get a timeout error.  Since the firewalls seem to be configured to allow this (it currently works for the other 2 mail server/email listeners), I can't figure out why it won't work for this account.  All of the accounts are the same domain and host name, so there shouldn't be anything different.  Anything simple I'm missing, or is this a rabbit hole for system administrators to address?