At the end of last week, Windows Live Messenger users reported that they were unable to send YouTube links to their buddies. As you can see in the screenshot, any message containing a link to YouTube.com failed to be sent.

The issue was rectified by Microsoft over the weekend, but people started wondering what put YouTube.com into their blacklist database. Since YouTube is now owned by rival Google, people started speculating that Microsoft has intentionally put YouTube in their blacklist.

Microsoft has a practice of blocking URLs or domains which may contain malware or virus. Some malicious scripts propagate by sending messages containing a link which infects your contact's computer. Microsoft has partnered with a third party to maintain a blacklist of malicious URLs.

They detect these harmful URLs based on various factors such as number of times a URL is sent, the frequency of the URL being sent, the number of accounts the URL is sent from, manually checking the URL, comparing with other "block lists", etc. On Friday, their partner accidentally blocked a set of IP addresses and that caused YouTube.com to be blocked.

I'm not really comfortable with the fact that Microsoft leeches on our chat messages to check for malicious links, but at the end of the day, they are doing this to protect millions of unsuspecting users from being infected. Hope they'll be careful next time.

Via: CyberNet [Screenshot: iStartedSomething]