Website hp41{dot}org camouflaged?

[rawi]

Hi

I wanted to include in a post a link to a website of hp41{dot}org. If writing it the normal way the hp41{dot}org was replaced by asteriks and it looked like this:
http://www.*****/LibView.cfm?Command=View&ItemID=210
Is this a bug or done by intention? And if so what is the reason?

Thank you

Raimund