emailgtw error authenticating to Office365 smtp server

Document ID : KB000007817
Last Modified Date : 14/02/2018
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Unable to configure the emailgtw probe settings using an Office365 SMTP server.

"Test" option in emailgtw probe SMTP menu fails and produces the following error in the emailgtw.log:

emailgtw: EHLO
emailgtw: Hello []
emailgtw: 250-SIZE 157286400
emailgtw: 250-PIPELINING
emailgtw: 250-DSN
emailgtw: 250-AUTH LOGIN XOAUTH2
emailgtw: 250-8BITMIME
emailgtw: 250-BINARYMIME
emailgtw: 250 CHUNKING
emailgtw: (cmd_test_smtp_login) smtp_open succeeded
emailgtw: AUTH LOGIN
emailgtw: 334 VXNlcm5hbWU6
emailgtw: (mm_login) getting username and password for host]
emailgtw: mm_login - found match []
emailgtw: <suppressed>
emailgtw: 334 UGFzc3dvcmW6
emailgtw: <suppressed>
emailgtw: 535 5.7.3 Authentication unsuccessful []

emailgtw probe version 2.83Office 365 SMTP server

This issue is associated with the authentication process to the Office365 managed by the Office365 Admin


Here is are some helpful links to troubleshoot this problem:

 1. Use Telnet to verify SMTP communication outside of the emailgtw probe

How to Use Telnet to Test SMTP Communication


 2. See the following link with a solution for the "535 5.7.3" SMTP error