Add New User from Site Admin does not send registration email

I have a wordpress 2.5.1 site setup on bluehost that is having problems sending new user registration messages to the new user.

It does send the new user message to the admin.

It does send the new user message to the new user, IF the register themselves from wp-login.php. But if the administrator creates a new user from the site admin area, the user does not receive the welcome email.

Is this the default behavior of WordPress? Or is there some way to fix it so that users created by the site administrator still receive the welcome email?