Email not realy private in profile URL

I mentioned that in some profile url the data from the emailaddress is used and the "." and the "@" are replaced by "-"

In some urls I only see pasts of the name but others crealy show the emal address.
Like these
http://www.eindhovendanst.nl/eigen-profiel/1717-shanto-ziggo-nl
Or
http://www.eindhovendanst.nl/eigen-profiel/1712-paul-klijn-hotmail-com

I don't know why some do and some don't but it feels like a very unwanted bug.
People can register using EasySocial or the integrated JFBConnect Facebook or Google buttons. Maybe there is a clue.

I let users login with there email address and on registering have the username generated from the email address.