How to set up Sender Policy Framework (SPF)

Adding a SPF record to your DNS can help prevent email spoofing of your domain.  
If your organization only sends messages from SmarterMail then add the following TXT record for the domain:
    v=spf1 mx -all
This setting is for Smartermail customers who use servers to send. The setting won't work for people who use Google or other mail systems.