False Positives Continue to Plague Permission Efforts

During the second half of 2003, the top 18 ISPs incorrectly blocked or filtered 18.7 percent of permission-based e-mail, up 1.7 percent from the previous six months and 3.7 percent from the same period in 2002, according to Return Path's latest "E-Mail Blocking & Filtering Report."

Based on the delivery, blocking, and filtering rates of 30,000 e-mail marketing and newsletter campaigns, the study found that NetZero had the highest rate of non-delivery at 37.7 percent, followed by SBC Global/Yahoo! (26.7 percent), Mac.com (26.2 percent), Verizon (26 percent) Mail.com (25.5 percent), Road Runner (24.5 percent), AOL (23 percent), Comcast (22 percent), Yahoo! (21 percent), Compuserve (20.5 percent), Cox Communications (19.5 percent) and Cablevision (17.5 percent).

In contrast, Earthlink had the highest success rate, blocking only seven percent of permission-based e-mail, followed by BellSouth (8 percent), AT&T Worldnet (10.2 percent), Hotmail (12.5 percent) and MSN (13 percent).

Overall, Yahoo had the biggest drop in delivery performance during the second half, with Yahoo!Mail blocking 16 percent more permission-based e-mail and SBC Global/Yahoo! blocking 14 percent more. Conversely, Mail.com had the biggest improvement in delivery performance (up 12 percent), followed by CompuServe (up 10 percent). On the whole, Return Path attributes this shift in delivery rates to "increased sophistication of machine-learning content filters, changes to unknown user thresholds, and changes to the allowable subscriber complaint ratio."

Other findings include:

• Of the more than 100 companies studied, delivery success rates varied widely, ranging from 50 to 100 percent. According to Return Path, the wide gap in delivery rates is due in part to different list generation tactics and procedures used by mailers; and

• Among industry sectors studied, marketing (50 percent) had the highest non-delivery rate, followed by greeting cards (46 percent), travel (32 percent), pharmaceuticals (22 percent), publisher (20 percent), community (11 percent), online retailer (6 percent), online services (2 percent) and telco (2 percent).

The study was conducted between July 1 and December 31, 2003 using Return Path's Mailbox Monitor service. The 18 ISPs tested represent more than 80 percent of the address domains contained in most corporate e-mail databases. To download a copy of the study, visit www.returnpath.biz/download/index.php?id=blockingfiltering0304.