send an email every time i post a new topic????

There are many plugins that will accomplish that, personally I use the Subscriptions option in the Jetpack plugin.

http://jetpack.me/support/subscriptions/

Using the Jetpack option will let your readers have the option to be notified whenever a new post is published.

Take a look at these, one of them may get you that functionality if you don’t want to use Jetpack.

http://wordpress.org/extend/plugins/search.php?q=subscriptions