SMTP authentication failing with third party application

Question

Hello,

I am trying to send email from third party application (Knime Analytics Platform) to external user. I tried setting up "App Password" and “Authenticated SMTP” option is enabled. We have MFA enabled on our account. Upon checking with IT team I got a below information from logs, I made sure that my Username/Password ( used app password too) is typed correctly

I followed steps mentioned in this article: Option 1: Authenticate your device or application directly with a Microsoft 365 or Office 365 mailbox, and send mail using SMTP AUTH client submission t=

I am getting error: Error while communicating with the smtp server: javax.mail.AuthenticationFailedException

Please suggest if you have any ideas to solve this issue. Thank you.

Answer 1

The problem there is that the application cant respond to the MFA prompt.

Can you create a service account that doesnt require MFA or use Oauth instead? That would allow this to work

https://learn.microsoft.com/en-us/exchange/client-developer/legacy-protocols/how-to-authenticate-an-imap-pop-smtp-application-by-using-oauth

You could use a conditional access policy to limit the account logons to specific IP addresses as well to help protect it.

Answer 2

You can't have MFA enabled for the account.

Ensure also that SMTP auth is enabled for the mailbox:

https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission#enable-smtp-auth-for-specific-mailboxes