AOL spam filters block e-mail from EarthLink and others

Spam-filtering software from America Online Inc. may have overstepped its bounds and blocked e-mail from customers of Internet service provider EarthLink Inc. for more than a week, resulting in potentially more than one million messages that were undelivered and lost for good.

Atlanta-based EarthLink estimates that 100,000 to 150,000 e-mails sent by its customers to users of AOL were blocked daily, for approximately 10 days. That could mean that more than one million e-mails were blocked, although EarthLink couldn’t say for certain, since the undelivered mail didn’t bounce back to the sender. Instead the e-mails were collected in a “bucket” and couldn’t be retrieved.

In a statement, an AOL spokesperson said the filtering software mostly did its job – it blocked spam.

“One of our top priorities is protecting our members from spam, and as part of that effort our system automatically shields our members from those servers that are sending significant volumes of spam. A small percentage of EarthLink servers fell into that category, but we’ve worked with EarthLink,” he said.

AOL blocked legitimate messages because they came from the same servers at the same time as e-mail from spammers that used EarthLink to send electronic junk mail, the AOL spokesperson said.

The AOL software kicked in when an unusually high number of e-mails coming from one IP address arrived at AOL servers at the same time, Baker said. While some of those e-mails were probably coincidental and not from spammers, AOL determined that the spike in volume could only mean a spammer was trying to flood mailboxes with unsolicited mail. Therefore AOL’s antispam software automatically kicked in to block all e-mail from that IP address.