Have a quick read through this posting where I was testing out this problem and also found a short term solution:
http://www.headvert.com/Forum/tabid/145/forumid/31/threadid/191/scope/posts/Default.aspx
I'm not sure if it is an editor problem because the underlying link in the forum appears to remain intact and correct (i.e. the <a href....>)
I have also seen it happen from this forum (here at dotnetnuke.com) and the short-term solution I found was to drop the www part of the link. So I'm going to drop that link in again and remove the www part:
http://headvert.com/Forum/tabid/145/forumid/31/threadid/191/scope/posts/Default.aspx
So what I have observed so far is that in the forum, both links will have created an underlying <a href....> with the link that was dropped into the editor and will "hold/save" them correctly. However, in the email notification that gets sent out you should see the first link incorrectly linked but the second correctly.
As I said: Don't know if it's going to happen in this email...
Okay, dropping the links onto this editor (I'm using Firefox at the moment) didn't generate the underlying links when I took a look at the HTML view so I'm going to insert them to test this theory:
Link 1 with wwwLink 2 without wwwBoth links above should work from here but if you received an email notification then the 1st link should not work.