Email marketing is about connecting with your customers over email. In a broad way, every email you send a potential customer is email marketing but I focus a little more on direct email marketing, and newsletter subscriptions.
While many businesses overlook the power of email marketing, a look at your inbox will show how often it’s used by large companies like Pinterest and YouTube to market directly to you and keep you interested in their product.
In my opinion, email marketing is one of the most reliable (and underused) Social Media Marketing (SMM) tools available.