All You Need to Know About E-mail Authentication

Sender Policy Framework (SPF) is an IP-based technology that verifies the sender IP address by cross-checking the domain in the e-mail address listed in the visible “mail from” line of an e-mail against the published record a sender has registered in the Domain Name System (DNS). When you publish an SPF record for your domain, you declare which IP addresses are authorized to send out e-mail on your Domain Name System behalf. SPF allows senders/marketers effectively to say, “I only send mail from these machines (IP addresses/servers). If any other machine claims that I’m sending mail from there, it is not telling the truth.”