I think email marketing or even marketing in general was the one thing I never focused on that much, thinking that "the game will market itself because, d'oh, my work is too frikin awesome
" and EVERY time it bit me in the back.
It's super important to be aware of this aspect as an indie dev, it took me +- 10 years to learn that, and even if it feels like "yet another thing that I have to take care of, as I don't have enough on my plate already..." without it you're pretty much dead in the water.
If you can hire someone to take care of it, do it, but put as much effort into marketing as you do into making the game, if you want a chance for success.
Awesome post Ramos!