Send email with OAuth2 flow for Office 365

Question

I have implemented the solution using this article:
https://www.limilabs.com/blog/oauth2-password-grant-office365-exchange-imap-pop3-smtp
but this approach needs the SMTP AUTH to be enabled in the 365 tenant.

Then the question come out, why i need to implement a new authentication method to avoid using SMPT AUTH and still need it to use new authentication method?

There is a method to send email with mail.dll without using SMTP AUTH?

If the answer is no, it will comes in the future?

Answer 1

OAuth 2.0 Password Grant flow (and all other OAuth flows) are not considered Basic authentication.

Microsoft disabled Basic authentication for IMAP and POP3.
They haven't disabled Basic authentication for SMTP (or rather it is possible to turn it on).

Sometimes SMTP AUTH term is used as an equivalent of Basic authentication - this is not correct. SMTP AUTH is a command that allows client to provide a user/password combination to the server, however password may be an OAuth access token.

All OAuth 2.0 flows use SMTP AUTH command to provide an access token.