When Is Microsoft Disabling Basic Authentication?

Today, we are announcing that, effective October 1, 2022, we will begin to permanently disable Basic Auth in all tenants, regardless of usage, with the exception of SMTP Auth.

Does Office 365 use basic authentication?

All access to Office 365 will be over Modern Authentication. ... Clients that don't support modern authentication will no longer be allowed to access Office 365 over basic authentication. Office 365 Administrators will need the Modern Authentication supported PowerShell module to connect to online Exchange.

What is MS basic authentication?

Basic Authentication relies on sending usernames and passwords -- often stored on or saved to the device -- with every request, increasing risk of attackers capturing users' credentials, particularly if not TLS protected. Basic Authentication is superseded by Modern Authentication (based on OAuth 2.0).