Spammers aren't the only ones the Microsoft Network has been blocking since it spam-proofed its servers.
Some MSN members also have been inadvertently blocked from sending mail through the MSN system, a Microsoft spokesman confirmed.
As reported earlier, on Thursday, MSN, the showcase online site for Microsoft, reconfigured its mail servers to stop accepting outgoing mail from non-MSN customers, a move praised by those who work to fight spam.
Many ISPs do the same thing to keep junk emailers from using their mail servers. Spammers often will look for open SMTP servers to relay their bulk email. The practice is known as "hijacking," and antispammers for years have urged all system administrators to close down the servers to outsiders.
Microsoft reconfigured its servers so they would only accept mail from IP addresses belonging to MSN customers, a spokesman said.
Unfortunately, however, in the process of blocking out all non-MSN IP numbers, it blocked some MSN IP numbers as well. The spokesman said Microsoft had gotten the numbers from its access service, backbone provider UUNet. As a result, some customers were unable to send mail for several days. Others were unable to send email because they did not reconfigure their email programs properly.
While some users were upset by the problem, others praised Microsoft for fixing its servers and hoped the move would set a good example for those in the industry who have not yet done so.
"Microsoft deserves all of our thanks for keeping their systems from being abused by spammers as third-party relays," said Paul Vixie of engineering, consulting, and technical services company Vixie Enterprises and antispam advocate. "We of the Mail Abuse Prevention System hope that other national email providers will follow Microsoft's example."
While IP addresses are assigned dynamically, it was unclear if the numbers that were blocked belonged to any particular region, although Canada seemed to be particularly affected.
MSN also could not say how many customers were affected. The company has refused to give out subscriber numbers in general for more than a year.
A spokesman would only say that very few people were affected and that the problem would be fixed by today.
That was small comfort to those who found their email blocked. One Canadian user said yesterday he has been unable to send email for a few days.
Another MSN user, a writer who uses email for work, said in an email message yesterday that "several clients called this morning fuming" because the email he had sent never made it to them.
"God knows how many of my e-mails have been lost since Microsoft installed this 'feature,'" he wrote. "God knows how many other MSN members' emails have been lost.
"Tech support told me to be patient," he added. "They gave me a condescending explanation of how the Internet works, and then said it could take up to a month for the email to arrive. 'That's just the Internet, you know. Not our fault.'"
Tech support people in some areas were, in fact, telling customers that the spam blocking procedures were causing outages. A Microsoft spokesman initially said yesterday that he was unaware of a problem.
After further checking into the matter, however, executives said they had discovered the problem. In addition, the changes in the server required that people who log onto MSN from other networks reconfigure their mail servers.
Microsoft had contacted those customers to tell them how to make those changes, the spokesman said.
This is not the first time MSN has had trouble with its email service. Last year, MSN members experienced a few frustrating outages due to overburdened mail servers. MSN upgraded its service, along with its email, in October.