Oh, I've seen these all over the place! It's just another way to spam the forums with links to their sites... they use general wording, like a type of introduction, but they hyperlink the words with links to their sites... they think if it goes through the PM system they won't get caught as fast as if they just posted on the forum... you shouldn't be worried about getting a virus just from opening the message, it's impossible for them to attach anything to the forum because it's restricted... they would have to hack in to be able to do anything like that...
if you do get a message that looks weird, open the message (DO NOT CLICK ON ANY OF THE LINKS WITHIN THE MESSAGE!) and you can use the report icon on the top right corner... looks like a triangle with an exclamation and should say "report" if you hover over it with your mouse... that way, it will get reported to all of us Mod/Admins and one of us will get in here to ban them ASAP!