AOL said Monday that the problem arose late last week when Yahoo did not notify AOL that it had changed its IP addresses on some of its servers, including those that have the Yahoo Groups e-mails. Because AOL was not notified, the company's servers identified the mail coming from Yahoo as spam, or unwanted junk e-mail.
"This has caused AOL users who are subscribers to Yahoo Groups to miss three to four days worth of e-mails," Robert Neill Jr., a publisher and moderator of 80 Yahoo Groups, wrote in an e-mail to CNET News.com. "Timely delivery of messages is of importance for many types of lists on Yahoo Groups, (such as) business and professional lists where contacts and information can result in lost business if information is delayed."
AOL said it has a filtering system in place to protect its subscribers against large volumes of spam coming from servers that the company is not familiar with. AOL said it works with companies such as Yahoo that deliver large volumes of e-mail to make sure their servers are "white listed," or given permission to send mail to AOL members.
"We're working quickly with Yahoo to address the issue and expect it to be resolved in the very near future," said AOL spokesman Andrew Weinstein.
Yahoo said it did not know about AOL's "white list," but as soon as it did, it began working on the problem with AOL.
"We worked very quickly with AOL, and the issue should be resolved in the very near future," said a Yahoo representative. The representative said Yahoo had changed the servers' IP addresses as part of routine maintenance.
Yahoo and AOL representatives said they did not know how many people were affected.
The problem comes as Internet service providers continue to combat spam but are faced with critical hurdles such as mistakenly filtering wanted e-mail. Last week, Microsoft upgraded its Hotmail service with a new filtering system aimed at wiping out annoying junk mail.
Last year, AOL's computers mistakenly identified Topica mailings as unsolicited bulk e-mail.
Yahoo Groups is a free service that allows people to interact with one another through a Web site and e-mail group. Yahoo said its service is advertiser-supported and is partially sponsored by advertisements inserted into the e-mail messages people receive.