SMTP OAuth device_code flow authentication problem

Question

I am creating a client that could make user connect to Exchange Online, and send E-mail as the logged-in user.

I have created the corresponding Organization, User and Application on Microsoft services, did the settings that seems necessary.

Conventional client like Thunderbird works no problem, but when I use the authentication message in AUTH XOAUTH2 it always returns "5.7.3 Authentication unsuccessful", I can't see where the problem is.

smtp_log.txt

smtp_oauth_test.txt

Answer 1

Hi,

It looks like your question is more related to Development .To better solve your problem , I will add “Exchange Development” tag.

But based on my personal experience, this link seems mentioned the same problem to yours: azure active directory - Office 365 XOAUTH2 for SMTP on native clients 535 5.7.3 Authentication unsuccessful - Stack Overflow