Not receiving email - "5.7.3 Client was not authenticated"

Problem description

The Hub Transport server is set for authentication out-of-the-box. Its role was not really designed to be outward facing towards the WAN. For Norman to deliver mail to a client with a Hub transport server, you need to set your Receive Connector to allow anonymous access.

The SMTP logs of a test message from Norman’s delivery server to a Hub Transport server, which has not turned anonymous access on, will return the standard Client not authenticated message:
“return-path address <> rejected by : 454 5.7.3 Client was not authenticated.”


  1. To alleviate this problem, please use the below command in Exchange Management Shell (EMS):
    set-ReceiveConnector -identity “Default <SERVERNAME>″ -PermissionGroups AnonymousUsers
    Note: Replace <SERVERNAME> with the actual name of your server.
  2. Restart the SMTP services.

Date Published: 2012.06.06   Date Updated: 2012.11.14