Blacklisters Increasingly Tracking URLs

In the latest twist on e-mail filtering, anti-spammers are increasingly compiling lists of the URLs that appear in messages that hit spam traps and blacklisting the Web addresses.

As a result, any company whose Web addresses appear in the bodies of messages that hit spam traps will increasingly find all e-mail that contains those URLs blocked—possibly even e-mail to their own customers.

“This is particularly important for people that have their creative sent through third-party lists,” said George Bilbrey, vice president and general manager of Return Path’s Delivery Assurance division. “It means even mail to a good, clean, solid list can get filtered.”

One example of an anti-spam blacklist that tracks Web addresses that appear in the bodies of spam is SURBL [pronounced surble].

“Unlike most other [blacklists], SURBLs are not meant to identify spam senders by their message headers or connection IP addresses,” says introductory copy on Surbl.org. “Instead they allow you to identify messages by the spam sites mentioned in their message bodies.”

Bilbrey added that inbox providers are increasingly using SURBL and other URL-based blacklists to help them filter spam out of incoming e-mail.

“It means you need to be very careful with affiliate programs and third-party list rental to make sure that the people you’re renting from have the very highest quality lists,” he said. “Ideally, you should also be monitoring those sorts of blacklists to make sure your domains aren’t on them.”