We recommend that you create a Sender Policy Framework (SPF)
record for your domain. An SPF record identifies which mail servers are permitted to send
email through your domain. This prevents spammers from spoofing your email address and sending spam. A query of the SPF record will show whether or not email coming from your domain is authorized. If the message is shown to the recipient mail server as not to be coming from a valid server, it can be flagged as spam. Having an SPF record helps to keep your mail server from being blocked entirely from a service like Google, Yahoo, etc. because of spam reports.
It's relatively easy to set up your SPF record. Log into your control panel. Go to Email Authentication in your Mail group, and simply click "Enable" under the SPF record description.