Email Marketing can be a very powerful tool indeed just like any other marketing. The difference being with Email Marketing your potential client as potentially already vetted meaning your ROI would be higher.
With Email Marketing the person receiving the email is already interested because they would of signed up ( by law you need a recipients permission to be subscribe to a mailing list ) .
This is such an easy and affordable form of marketing it makes sense to take advantage.
If you have an online shop you can ask the customer to sign up as they check out or you can have a sign up form at the bottom of any website.
You can tempt users to sign up by offering them a discount or special offers etc and who doesn’t love a special offer.
One of the best priced and most used is Mailchimp . It has a FREE tier which allows 2000 subscribers and allows you to send 12000 emails a month which would be 6 emails to each of your 2000 subscribers. So this is more then enough to get started with. You can see the other perks on their pricing page
Mailchimp also as stats like open rates etc so you can gauge interest so you can change the email content if need be.
Please note there are other services out there but Mailchimp was the best one for the price and ease of use.
If email marketing is something you are looking to get set up and you need a hand let me know.