Hotmail outage hits Apple and broadband users

Spam sending botnets could have caused Hotmail email outage

A problem with Microsoft's Hotmail and MSN email service is preventing users from multiple providers from sending messages to the Microsoft email services.

Users of the mail application in Apple's OS X operating system on Monday started reporting that email messages addressed to Hotmail and MSN addresses weren't being delivered. The problem doesn't occur if a copy of the message is sent to the user's own account. Changing the priority setting from 'normal' to either 'high' or 'low' also provides a workaround, users reported on the forum.

Microsoft was made aware of the issues with Apple users on Tuesday. The company acknowledged the problem and said it has been working on a solution. As of Thursday afternoon there was still no fix and Microsoft couldn't provide any background information on what was causing the problems.

Subscribers of the Comcast broadband internet service reported similar issues last week. The provider started blocking all outgoing email sent to Hotmail and MSN accounts after these messages were queuing up on their servers. The issue was resolved on October 20, as vnunet.com reported earlier this week. 

Users of the Canadian broadband providers Rogers and Cogeco have reported similar issues to the ones that face Apple and Comcast clients.

Some user complaints on public fora go back months. Microsoft's refusal to discuss the situation made it impossible to verify those claims and determine if they are related.

Apple PR did not respond to repeated requests for information. A spokeswoman for Rogers said that she wasn't aware of any issues. Cogeco did not return a phone call seeking further information. A spokeswoman for Comcast declined to provide information about the technical background of last week's outage.

Andrew Lockhart, director of product marketing for email security vendor Postini said that the problems appear to be spam-related. An action by Microsoft could have triggered a response from the providers, leading to the outages.

"These things almost become like a comedy of errors," Lockhart told vnunet.com.

Broadband providers provide rich hunting grounds for botnet operators. After infecting the computers of broadband subscribers with an internet worm, they use them to send out spam email messages.

Providing a possible explanation for what could have happened in Hotmail's case, Lockhart said that email providers commonly decrease the speed of incoming email connections when they experience a surge of spam email from a single provider. As the provider notices the large pool of messages that have yet to be delivered, it could then temporarily block all all messages going out to that particular provider.

While in that case both Microsoft and the provider are responsible for the outage, the core problem lies with the providers because they fail to take a common sense approach against botnets on their networks, argued Lockhart.

"The ISPs are taking shortcuts to this solution because they don't have the technology in place in a fine-grained and sensitive manner," Lockhart said. " There is no reason for Auntie Martha's computer to send 10,000 spam messages per minute."
The problems that are reported by Apple users appear to be related to their providers rather than the software that they are using, said Lockhart.

Email messages contain information identifying the client that was used. Theoretically however Microsoft could block all emails sent from Apple's Mail client, for instance because spammers are spoofing the Apple Mail headers in an attempt to dodge spam filtering software.

Michael Perone, vice president of marketing for spam and spyware filtering provider Barracuda Networks too argued that the problems are most likely linked to spam issues.

"This seems to be an issue with blacklisting," Perone told vnunet.com.

Barracuda has more than 25,000 spam filtering appliances deployed around the world. The data collected from those machines indicate that providers are starting to use blacklists more aggressively, Perone said.

"This is due to the growing number of zombie PCs and botnets that are used for spam operations."