Hotmail's antispam measures snuff out legit emails, too

Microsoft representatives say the upsurge in spam - which they estimate to be about 40 per cent in the past year - has forced them to employ new techniques to safeguard Hotmail users and infrastructure. Once upon a time, messages were flagged largely based on the domain that sent it (e.g. Cyberpromotions.com) and by keywords - (think "get rich quick") that were embedded in them. With the growing use of image spam and botnets used to blast them to every corner of the globe, Microsoft has had to employ additional measures.

"The rules of deliverability have really changed," says Brian Holdsworth, senior product planner for Microsoft safety technologies, a group that is responsible for fending off the spam menace. "It's no longer just me, my email address and the domain I own. It's where I'm hosting it at and the reputation of my host."

Holdsworth was unfamiliar with Firth's case, but he speculates Firth's domain may be blocked because the provider hosting it may be home to a large number of infected machines. In such cases, all sites sitting on top of the host can be affected. Microsoft provides a service that allows hosts to review the reputation assigned to them by SmartScreen. (The service is not available to customers such as Firth.)

Microsoft representatives say they are making important progress in combating spam, having reduced the amount of junk mail landing in inboxes by half in the past year. What's more, of about 5bn messages sent to Hotmail users daily, as many as 4.5bn are spam. They say they are committed to resolving the problems such as Firth's and add that most large email providers are struggling with the same issues.

Perhaps, but according to Dominic Ryan, who runs a website called IIS-Aid, other providers do a better job. Ryan found that email his site tried to send to users with Hotmail addresses was also getting blocked, and he got to wondering how many other services might block his domain. So he set up a simple test in which he sent an identical email to accounts with ten different services.

Only one account - you can probably guess from which provider - failed to receive it.

"I have basically given up on Hotmail support," says Ryan, whose credentials include being a three-time Microsoft IIS MVP. He now bans the use of Hotmail addresses for users registering on his site and sends an automated response to those sending messages to fellow users with Hotmail accounts warning that the dispatches will probably not get through.

Of course, the biggest friendly-fire casualties in Microsoft's war on spam are the Hotmail users whose legitimate emails are killed before ever landing in their inbox. Firth and Ryan have been working diligently to alert these individuals to the problem, but so far they're warnings have gone unheeded. ®