18.7% of Legitimate E-mails Not Getting Through: Study

Internet service providers are blocking substantial amounts of permission-based e-mails, mistaking them for spam.

ISPs failed to deliver 18.7% of opted-in e-mails sent to their subscribers between July 1 and December 31 2003, according to a study by e-mail performance management company Return Path, Inc., New York.

The failed deliveries mark a 1.7% increase over January through June 2003 and a 3.7% increase over the same period in 2002.

NetZero topped the list with the highest percentage of non-delivery at 37.7% of permission-based e-mail, followed by SBC Global/Yahoo at 26.7% and Mac with 26.2%. Earthlink was reported to have the highest success rate, with only 7% of legitimate e-mails blocked, Return Path said.

"Most permission-based e-mailers do not take adequate steps to ensure the successful delivery of their e-mail, which hampers campaign conversion rates and ROI," Matt Blumberg, the CEO of Return Path, said in a statement.

Monitoring key delivery metrics and ensuring compliance with best practices should contribute to a decline in non-delivery rates, the company said.