Sender Policy Framework

Does SPF stand for Sender Permitted From?

It used to, but that name turned out to be too slippery for the human mind to grasp, so we in early February 2004 we changed it to the more accurate "Sender Policy Framework".

Trivia: for marketing reasons we picked the acronym before we picked the expansion. First we went to Google to see if SPF already stood for anything outside the sunblock world. It is the name of a networking concept — Shortest Path First — but that's okay; every good acronym deserves at least two expansions. So we chose that name for the brand and today we're #1 on Google for "SPF".