Posted by Jason Hart on February 27th, 2008

The spammers are at it again by exploiting the web email services of Google, Microsoft, Yahoo! and other companies to send spam and bypass regular junk filters.

In recent weeks you may have seen some spam arriving that looks like a reply or response to an email that you sent. This is not just a formatting ploy to get you to try and read the email, in reality it’s the next clever move by mass email senders.

Essentially the spammers are registering a large number of online web mail accounts with the major ‘trusted’ online providers and subsequently setting up auto responder messages / out of office replies that contain their spam. They follow this by sending lots of emails at the new accounts with a reply-to address of the people that they wish to send their spam messages to.

The resulting effect is that messages get sent back out from the servers at Google with the correct location, headers, IP, signature etc which allows the mail to be approved by most spam filters and land straight in your inbox.

Software providers are starting to get their junk filters trained to deal with these messages, but it is a difficult task trying to not have to many false positives that potentially ’spam’ important emails due to the genuine ‘from’ details contained within.