In the ever-changing online world where new apps are developed every day and we're constantly jumping from one social network to another, email is practically archaic. And, yet, it still remains one of the best forms of marketing. A big reason for this is because we no longer have to be at a computer to check our emails — we carry them in our pockets! No matter what the critics tell you, email marketing is still a relevant form of marketing and here's why:

Email newsletters allow you to reach your customers wherever they are.

According to ExactTarget's "Mobile Behavior report" (2014), 91% of consumers check their email at least once per day on their smartphone, making it the most used functionality. Another study found that the number of people who use their smartphones for checking email is higher than the number of people who use it for making actual calls! Email newsletters allow you to peak your customers' interest throughout the day no matter where they are.

It's a non-spammy way to get in touch with your customers.

In order to send your customers emails, they have to subscribe. This puts the ball in their court to decide whether or not they want to hear from you. I don't know about you, but I guard my inbox closely. If I've given you my email address, it's because I want to hear from you. Likewise, the people you are sending email newsletters to want to hear from you. This is a huge advantage compared to other forms of marketing where you have to sift through demographics to find your target audience. With email marketing, your audience is already there and waiting for your message.

It's easy, cheap, and effective.

Very few things in the marketing world can claim all three of those adjectives, but email marketing can! Most email marketing services today, like Constant Contact or MailChimp, base the cost of a subscription on the number of people you have in your contact list. While this price will vary for everyone, it is normally much cheaper than other forms of advertising. It's also easy to use with many modern templates that can be customized to fit your brand. Finally, it is effective. We'll let the facts speak for themselves:

• For every $1 spent, $44.25 is the average return on email marketing investment. (Experian)
• 95% of those who opt into email messages from brands find these messages somewhat or very useful. (Salesforce)
• 44% of email recipients made at least one purchase last year based on a promotional email. (Convince & Convert)
• Email is nearly 40 times better than Facebook and Twitter at acquiring customers. (McKinsey & Company)