I am still getting NDR from clients using Symantec:-

The message was rejected because of Sender Policy Framework violation -> 553 SPF (Sender Policy Framework) domain authentication;fail. Refer to the Troubleshooting page at;http://www.symanteccloud.com/troubleshooting for more;information. (#5.7.1)
Remote-MTA: dns;server-11.tower-193.messagelabs.com

Symantec is not talking to me