Windows Live Messenger is no longer blocking legitimate websites, the company revealed on May 11, after users reported that the instant messaging client was preventing access to various URLs including Google's YouTube video web property. The first complaints came from users who discovered that it was impossible to share YouTube videos with their Windows Live Messenger friends if they typed the full URL. All items featuring "www.youtube.com" as either text or link were blocked.

"We had a problem from Friday night to Saturday morning where our Messenger service was incorrectly blocking some legitimate IP addresses. We sincerely apologize for any difficulties this caused our users. And we want to thank those of you that reported this problem to us so that we could quickly fix it. Because of your help, the incorrect block was only in place for a few hours", explained Dharmesh Mehta, the leader of the Windows Live Messenger product management team.

Mehta added that all the legitimate URLs that had been blocked had been so by accident, as the Redmond company did not request any websites to be blacklisted at the end of the past week. Furthermore, Microsoft itself has nothing to do with the URL blocking process, as all such actions are dealt with and managed by a partner company.

"The blocks were made by our partner as a result of their process to block harmful URLs", Mehta said. "We are still investigating the specific reason our partner made these incorrect blocks and we will work with them to improve their process for detecting harmful URLs while not blocking safe ones."

Microsoft is constantly working in order to bulletproof its products against threats in order to protect end users. The latest issue with the instant messaging client is just an accidental result associated with the process of blocking malicious URLs along with malware in Windows Live Messenger.

"There are a number of factors that can be used to determine whether a URL is potentially harmful: 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. When a URL is deemed harmful, a block can be instated for a specific URL (i.e. www..com/) or an entire domain (i.e. *..com)," Mehta stated.

Windows Live Messenger 8.5 can be downloaded from here.