Force Flow already gave a good answer.
I just have to add something to make it a bit clear.
Email Marketing is 'still' important because studies still show that sending offers through emails are more likely to convert readers (meaning they will purchase your product/service).
Of course, it is not that easy as it seems. Most of your time will be spent on analyzing the behavior of your market. That way you could do email marketing in the best and most personal way.