Update (below): Microsoft says it has "long" been censoring users

Tech giant Microsoft is actively intercepting and censoring conversations in its Windows Live Messenger program, utilizing a block list to prevent users from trading links to a popular peer-to-peer media sharing website known as The Pirate Bay.

While it's not surprising that a corporate block list would include The Pirate Bay, one of the Internet's most notorious havens for media sharing in violation of copyright laws around the world, at least one branch of the website devoted to legal peer-to-peer sharing is also being blocked.

In a trial-run Monday morning, Raw Story discovered that Microsoft is also blocking "The Promo Bay," where artists submit their materials to be discovered by a mass audience.

Artists the world over use The Promo Bay to help develop a global fanbase, utilizing the very technologies that have caused such consternation among the entertainment industry's largest players.

Microsoft, it would seem, does not like that.

While many major social websites, such as Facebook and Twitter, use block lists to help ensure their users' safety from malware and viruses, Microsoft has taken it a step further with Windows Live Messenger. Other services merely offer a warning that a link may be unsafe, but Microsoft appears to be actively denying these links in real-time chat conversations.

The result: Any attempt to share a link to The Promo Bay from Windows Live Messenger is quickly shut down, and the other user sees nothing. The chat client responds by saying:

That same link, shared on Facebook and Twitter, goes through without problem. Attempts to share The Promo Bay on AOL Instant Messenger, Google Talk and other popular chat services were also successful the first time. Those services also do not offer a warning that the domain may be a threat to users.

The block lists in use for Windows Live Messenger were first reported over the weekend by Torrent Freak, a tech blog that focuses on peer-to-peer media sharing issues. They noted that while The Pirate Bay was blocked through Live Messenger, other torrent sites that offer identical infringing content were not affected.

A Microsoft public relations agent said they were researching the issue, but had not responded with any relevant information at press time. The Pirate Bay did not respond to requests for comment.

Update: Microsoft says it has "long" been censoring users

Reached for comment, a Microsoft spokesperson told Raw Story that Windows Live Messenger has been filtering users' messages for quite some time now, adding that they use the company's SmartScreen technology to censor links to spam, identity theft scams or malware.

"Windows Live Messenger is set up to help ensure customers receive IMs only from people whose IMs are welcome and has long had the capability to block certain content from being transmitted in an effort to protect our customers," the spokesperson said. "Before anyone can send customers an IM, those customers must first agree to add the sender to their Contact list; this helps protect customers from unwanted IMs from strangers and from annoyances such as spam and spim (spam via IM).

"In addition, we use SmartScreen® technology to protect our customers from malicious and unwanted content including phishing, malware and spam. We block instant messages if they contain malicious or spam URLs based on intelligence algorithms, third-party sources, and/or user complaints. Pirate Bay URLs were flagged by one or more of these and were consequently blocked."

Raw Story Senior Editor David Edwards contributed to this report.