A post from Italian website HTNovo reports that Microsoft has added 11 CCleaner domains to a blacklist on its official support site Answers.
It's quite common to see forums block specific websites, such as those that are malicious in nature or problematic for other reasons. However, it's very rare to see legitimate websites blocked on official forums of large companies.

The Italian website reveals that the domain www.cleaner.com is one of the domains blocked by the company but does not mention the other ten that Microsoft added to its blacklist. The image above shows the URL of a hidden forum (moderators forum) that lists all the blocked domains. Last you will see ccleaner.com.
A quick test on the Microsoft Answers forum confirms that the domain ccleaner.com automatically changes to **** when included in a post. It does not matter if the protocol or www is used, the domain changes automatically after the post.
Why did Microsoft block this specific domain? No one can say for sure.
But let's recall the application's progress:
- CCleαner: caution installing the CCleaner Browser
- CCleαner remove it immediately from your computers
- CCleαner 5.50: Disabling automatic updates
- CCleαner new scandal with the application
