Server says [AUTHENTICATIONFAILED] Authentication failed

The above is the exact error message that I’m receiving trying to login (initial setup and then after when hitting send/receive) using version 6 on a Windows 8.1 tablet and entering my microsoft office 365 account using my custom domain name. I’ve tried this (which works using any Outlook client), my onmicrosoft account name which I no longer use to login and neither works. What ends up happening is an IMAP and smtp setup and attempt to use the diagnose button doesn’t help as I am repeatedly prompted for a password. Then I get “Your credentials were rejected.” Using the stock mail app and adding an account, my custom email address and password worked flawlessly.

Hi, I will need your SMTP and IMAP logs, go to tools - settings - advanced, check SMTP and IMAP under your account, apply and restart eM Client.

Try to authenticate with server and after that send logs to galis@emclient.com together with this topic’s URL in subject.

then you can turn logging off.

Jan