WordPress MU

i installed word press mu in my website named"tvjosh.com".

in that when a user register, it is not sending any email to the user.
for activation.

i created one user from admin panel(for testing), it is creating user as well as blog
in admin side. email sent with password and username.

what is the problem ??

i got mail with an activation link
http://bhavani.tvjosh.com/wp-activate.php?key=922773cf10622aa6.

while opening it throws can't find the server at bhavani.tvjosh.com.
please help me to solve this problem.
thank you
bhavani.

Follow the directions in the readme file. For subdomain blogs you need to activate wildcard subdomains in both Apache and your DNS records.

for user
email sir??????

You, as the site OWNER , have to finish setting up things on the server so the user blogs will show up properly.