#160009: The e-mail address ’emaill address’ is unknown

Bumped into this error when setting Office 365 Relay in my Local SharePoint On-premise server for outgoing email.

I have done the following steps -> http://fmuntean.wordpress.com/2008/10/26/how-to-configure-iis-smtp-server-to-forward-emails-using-a-gmail-account/

Ensure you have done the add SMTP Feature, IIS 6.0 SMTP Virtual Server running.

The below check/config works for me


  1. Go to your IIS 6.0 and right click SMTP Virtual Server properties.
    smtp relay email address unknown error - properties
  2. In the Server properties, go to “Security” tab and ensure the Service Account (or whatsoever account) that needs to do the mail sending, is added into the operators list.
  3. smtp relay email address unknown error
  4. That is it! You can refer to my post Powershell script to test SharePoint Send Mail

One thought on “#160009: The e-mail address ’emaill address’ is unknown

  1. Eric Schrader

    Hmm, I still get the same error. I have added all of my service accounts and reset the SMTP service. The final issue turned out to be I had to add my local IP to the allow list when using SendGrid.


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