Google and Microsoft announced basic authentication deprecation for their email services in 2022. Both companies consider Basic authentication as an outdated industry standard and thus they are suggesting its customer moving to OAuth 2.0 token-based authorization. Additional details can be found here.
These changes will have a limited impact since the services that were already usingSMTP with Basic authentication will not be impacted by the change.
For Google-Gmail, Basic authentication will be disabled starting May 30, 2022, and its still unclear if Google will allow it to be enabled post this date.
For Microsoft-Outlook, Basic authentication will be disabled starting October 1, 2022, but Microsoft will still allow it to be enabled as needed.