I had this problem too, I put in a plugin “new user email” which allow you to change the email that is sent easily including the landing page. so sent out the email as suggested above.
So it works OK except that the web admin link still works so the user has access to the web admin page. so the work around helps but does not solve the problems. I have spent some time trying to get this resolved including searching on this forum and gogling.
It seems strange that this is not a major problem for most wordpress users ??
Can anybody help please.
on wordpress 2.6.2
Thanks,
