SMTP Authentication Issue

Question

Hi Microsoft Team,

I have been sending emails using the SMTP method with a username and password for the past few years. However, I recently noticed that emails have not been sent in the last few weeks.

Upon investigation, I found that Microsoft has disabled basic authentication, requiring OAuth 2.0 instead. I have enabled SmtpClientAuthenticationEnabled, but I am still getting the error: "Authentication failed."

I have also verified that my OAuth 2.0 token has a valid expiration date, but the issue persists.

Can you please advise on how to resolve this? Additionally, if my subscription does not support OAuth 2.0 for SMTP, what are my options?