Earthlink:
Earthlink is a traditional ISP that offers Internet access in several different flavors including, dialup, broadband, wireless and satellite. Earthlink has grown their subscriber base through a series of over 100 acquisitions of smaller ISPs. For a complete list of all domains that Earthlink controls visit:
http://support.earthlink.net/mu/1/psc/img/walkthroughs/other/1694.psc.html
Earthlink presents deliverability challenges on two fronts. First, they employ a service they call SPAMBlocker, which uses commercial blacklist provider Brightmail to filter all incoming messages. Brightmail is a multi-layer content filter that leverages over 17 different technologies, including SPAM signatures, heuristics, reputation filters, language identification, and many proprietary methods. The end result is that SPAMBlocker determines whether your messages reach the inbox or get routed to the "Suspect" email folder (also known as a junk mail folder). We recommend keeping a keen eye on your content in order to avoid having your messages filtered by SPAMBlocker.
The second challenge with sending email to Earthlink members is their challenge-response system. There are several challenge-response systems in place today; however, Earthlink's is unique in that it never returns a response for commercial email. If you are getting a low response rate from Earthlink you may want to ask your list members to add your email address to their address book to get around the challenge-response issue. For more information regarding Earthlink's email filtering please visit:
http://www.earthlink.net/elink/issue24/focus_archive.html
