We love and recommend Sumo for email collection on your site.
Here are the steps to get your Sumo Account connected to your blog.
Step 1: Create Your Sumo Account Here: https://sumo.com/partner/blogpress
Step 2: Let us know when that's done so that we can activate the Sumo Plugin on your site.
Step 3: Once we've activated the plugin for you, go to SumoMe in the left menu and click on Connect Sumo. (See image below)
Step 4: Enter in the Sumo account credentials you created in Step 1.
Step 5: Now that you're connected, click on My Apps to turn on the apps you would like to use.
NOTE: In order to upgrade to Pro, you can click on Store from your WP Sumo Dashboard or from within the Sumo Home.