SMTP 535 Error

  • 7019823
  • 08-Sep-2016
  • 07-Aug-2017


Retain 4.x


We are finding "535 5.7.3 Authentication unsuccessful" errors in the worker log and we are unable to dredge from O365.


The 535 is an SMTP reply code, the email server is telling us: 535 SMTP Authentication unsuccessful/Bad username or password.

Confirm that the username and password is correct for the impersonation user. Note: In O365 passwords are required to be changed often.

Use Miscorsoft's online Connectivity tester to test Outlook autodiscover, if the test fails you will have to open a ticket with MS to reenable autodiscover.

Additional Information

This article was originally published in the GWAVA knowledgebase as article ID 2858.