WordPress MU

hi,
is there any way to send emails to every user/admin?
regards
bloggerbite

This plugin (but I did not use it):
http://wpmudevorg.wordpress.com/project/Mass-Mailer

There is also a different plugin in the premium section but you have to pay for subscription to download it.

thanks,but how to install the plugin? it's not really a .zip file so where i have to insert the code?

It's a zip file but you have to add ( .zip ) manually when prompted to save it. Then extract the php file from the zip file, then upload it to mu-plugins folder.

But there are certain instructions to follow in the description.