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An email asking for help on a problem floated by me and I thought it was an interesting enough one to blog about. First off all I had was the following error message from the MSCRM Exchange router:

#61042 - An error occurred while processing the outgoing e-mail message with subject "CRM ADMIN TEST MAIL CRM:0004015" for SMTP: http://crmserver/tenant/ for delivery through exchangeserver. System.Net.Mail.SmtpException: Mailbox unavailable. The server response was: 5.7.1 Client does not have permissions to send as this sender

The guy asking the question was trying to figure out what was wrong with CRM because that’s where the error was coming from. The problem is that he was looking in the wrong place. If you read the error carefully the last bit is actually the most important: The server response was: 5.7.1 Client does not have permissions to send as this sender

It actually states that the server (not CRM, but Exchange) responded with the client not having permissions to send. This is a fairly common issue and the resolutions fall into one of two options:

  1. The email address in the from can’t be used because you do not have permission to use it (duh) and you merely need to change the address to one you have permission to use.
  2. The second option is to enable SMTP authentication which should give you the permissions to send them mail.