Publish a SPF record in DNS Server to Our Mail Infrastructure

Sometimes our mail server are report in spam or blacklist. To solve this issue, we can to create a SPF (Sender Policy Framework) that is an e-mail validation system designed to prevent e-mail spam by tackling source address spoofing, a common vulnerability. SPF allows administrators to specify which hosts are allowed to send e-mail from a given domain by creating a specific SPF record in the public Domain Name System (DNS). Mail exchangers then use the DNS to check that mail from a given domain is being sent by a host sanctioned by that domain's administrators.

In internet exist many SPF Record Wizard for example:

http://www.microsoft.com/mscorp/safety/content/technologies/senderid/wizard/
http://www.openspf.org/

When you finish the wizard create a TXT record in your DNS Server with all information show in wizard results, for example in windows: