Hey, anytime Microsoft or anyone else decides to go to war against spammers, they can count on my support in their efforts. But it seems that their latest effort may even go so far as to pay them for the hard work.

Omar Shahine, lead program manager on Virtual PC for the Mac (the correlation between Virtual PC and Hotmail is unknown to me, but there is obviously some link there) posted in his July 7th blog about a technology that was fairly recently implemented on Hotmail to cut down on the amount of legitimate messages that end up in your Junk Mail folder.

The technology is dubbed “Boomerang” and is effectively a more granular version of the outgoing whitelisting technology already used by anti-spam products like SpamAssassin and ORF for Exchange. What is outgoing whitelisting? Well, put simply, when a user sends an email to a specific email address, that address is added to a whitelist which will allow email from that address to come through the spam filter and end up in the user’s inbox.

Boomerang takes the idea of outgoing whitelisting technology and goes just a bit further with it. Rather than adding an email address to a whitelist permanently, it only allows replies from a message sent from a hotmail user to a specific address, not all messages from that address. This allows any replies to a specific message to be filtered directly to your inbox, but any future emails could still be triggered as spam. [Read the rest]