Just in case someone has found this topic while trying to learn how to create a URL to send a PM (Private Message), here is a better way to accomplish it by using your actual username, rather than your user ID number.
Build the URL with the following:
http://www.waze.com/forum/ucp.php?i=pm&mode=compose
Optionally append a subject which will automatically be inserted into the PM:
&subject=add a subject here
Finally append this with your username:
&username=username
Here is a sample of a URL that would send me a PM with the subject, “Hello”:
http://www.waze.com/forum/ucp.php?i=pm&mode=compose&subject=Hello&username=GizmoGuy411