Answer

PROBLEM

When email is sent from the GFI MailEssentials relay server to your domain you see in the Message Delivery Log the Status Reply:

ENVIRONMENT

• GFI MailEssentials
• All Supported Environments

SOLUTION

1. Open Exchange Management Console > Server Configuration > Hub Transport > Default Receive Connector > Properties
2. Click Permission Groups
3. Check the box Anonymous Users
4. Click Apply then OK

For more information regarding setting up a GFI MailEssentials relay server, please see the below article:

http://www.gfi.com/support/products/gfi-mailessentials/How-to-install-MailEssentials-on-an-SMTP-Relay

​CAUSE

The error means that the Microsoft Exchange server is not configured to accept Anonymous connections.