A few months ago WordPress
released the Jetpack plugin
which has many awesome
One of it's nicest features is the ability to place a widget to asking visitors to supply their email address to get future posts via email.
The coolest thing about this is WordPress handles ALL of the email sending and such you don't even have to bother worrying about black lists, bounces, etc.
Next:Enabling and Installing Jetpack
1) Open your admin panel at domain.tld/wp-admin and login.
Hover over Plugins and select Add new. Search for Jetpack
Click install now under Jetpack
Activate the plugin
Connect to WP.com
Enter your Wordpress.com
user name and password, click authorize.
Back in your Admin Panel go to Appearance > Widgets and drag a Blog Subscriptions JetPack over to your widget area. Customize to your liking, and click save.
That's it! Now anyone can come to your site, enter their email address, and get an email with all your new posts!