Microsoft has spent the last year defining and positioning its SenderID standard, and is about to take a huge step forward, and put that standard to the test.
Beginning June 22, Microsoft intends to look for the SenderID authentication when it receives email. Microsoft will start out slowly, at first only letting MSN and Hotmail users know if SenderID is present (or not), or if the sender records don't match. Over time, probably later this year, Microsoft will begin searching for SenderID records more broadly, and begin weighing them more heavily in its spam-scoring systems.
SenderID is a well-designed solution that will make it harder for spammers, phishers and virus writers to spoof otherwise legitimate senders. As Microsoft steps up its efforts with SenderID, spamming and phishing will become more difficult and less rewarding.