How to upgrade my outlook account to modern authentication method?

spogprint Hi there - Based on what you are saying, you likely experience the Basic Auth deprecation which we announced a few months back, and has started to roll out as of this morning.  Based on what you are saying, you will likely need to talk with the team that manages your website, or the software package you are using on your website which sends mail.  Instead of using Basic Authentication to authenticate to your email, they need to use Modern Auth (OAuth).  The developer of the application or mail send functionality should be able to let you know if they have updated their sofware to support modern forms of authentication.