This is a really great question! A lot of people are unsure what to install, and even when an email app is setup there can be lots of hurdles to actually send great and regular emails that drive sales. To deal with this we created Concierge, which puts your email marketing on auto-pilot. There is no setup and nothing new to learn. It is the closet thing to email magic there is :)
Take a look at https://apps.shopify.com/concierge