February 05, 2008
ISPs like Hotmail have been pushing e-mail authentication for years. I've been talking about Sender ID and Hotmail for more than two years now and Meng Wong (now of Karmasphere) has been educating senders and receivers on why sender policy framework (SPF) is important since at least mid-2004. (This article first appeared in the 2007 edition of the Essential Guide to E-Mail Marketing.)