Searching for a plugin who sends mails automatically

Hello,

I have a small blog with only a few users, but I also want that my users are up to date at every time. So I am searching for a plugin, who automatically sends an E-Mail to my Users when I write a new post.

Or is it already integrated in wordpress and I am too stupid to find it?

I hope you understand what I want, because I am from Germany and my English is not the best ??

Marvin