SPF, which abbreviates Sender Policy Framework, is a certification system that aims at preventing the so-called email counterfeiting. Essentially, this means sending a message from one email address and making it appear to be sent from another one with the objective to scam in some manner the individual getting it. In the event that the SPF protection is activated for a domain, a record which contains all mail servers authorized to email messages with addresses under the domain is made. The record is saved on all DNS servers that route the web traffic worldwide, thus they all will identify if an email message comes from a trustworthy server or not. The check is performed at the very first server where the email goes through and in the first case the e-mail message is forwarded, while in the second it's discarded and it never reaches the supposed recipient. Applying SPF records for your domains will stop any unauthorized people from making use of your email addresses for harmful objectives.