Sender Policy Framework (SPF) is simple email validation system designed to detect email spoofing. By defining DNS TXT record for your domain you are able to tell remote receiver which mail servers are authorized to send emails with your domain.
More information about SPF can be found at http://www.open-spf.org/SPF_Record_Syntax/
Did you found bug in reporting? Please send us link to failing report, we will fix it as soon as possible.