First, it's really hard to get right.
Second, there are a handful of companies who do it correctly.
Most do not.
I'm one month into my new position at one of the top email marketing companies in the world. This hardly makes me an expert. In fact, I probably know less about email marketing than you might think. What I have come to realize however is that the opportunities are endless. Of the time spent on our mobile phones, 70% of it is in our email. This means if a marketer can get it right, they have your attention.
So how do you "get it right"?
Well, what you don't do is blast out messages with little to no thought behind why you're sending them and who you're sending them to.
If someone signs up to receive information from you, clearly they have some interest in your business, product, service, etc. Recognize that and use every opportunity you can to increase that interest. Build your brand. Keep your audience engaged.
Do coupons and special offers work? Yes. If they are good.
Do newsletters work? Yes. If they are well written. Don't regurgitate whatever content you already have on your website.
People already receive enough email as it is. So make your message count. Stand out in the crowd and your followers will love you for it. I'm always looking for great messages in my inbox. Rarely do I find it.
Be great. Be innovative. Be creative. Be the brand you aspire to be.