403 4.7.0 TLS handshake failed

We had an issue at a customer recently where they were unable to receive mail from certain external domains.

People that were sending mail to the customer we’re getting the bellow error “403 4.7.0 TLS handshake failed”

The issue was the receive connector on the customers Exchange 2010 Edge Server (Integrated with TMG) only had the TLS auth selected.

Resolution Steps

1. Open TMG Console
   
2. Go to Email Policy
   
3. Under SMTP Routes select your receive connector and double click
   
4. Select listener tab
   
5. Press Advanced
   
6. Check the following
   
   1. Basic Auth
      
      1. Offer Basic Auth
         
   2. Integrated Auth
      
   3. Exchange Server Auth
      
7. Uncheck TLS
   
8. Apply your Changes
   



Once TMG has applied the Config, Mails should all start working 