This is pretty much what I've experienced by accident. There were times in my app that I screwed up and had to send out some emails explaining or to users in so

This is pretty much what I've experienced by accident. There were times in my app that I screwed up and had to send out some emails explaining or to users in some particular situation where it was necessary to communicate something all responding way more than from the MailChimp and had to scramble to get it out, not caring about looks and was high response rate. Another occasion where I was lazy to pretty up the announcement email also had a much better click rate than MailChimp. I was suspecting something was off but seems this article is making me think it wasn't a coincidence. By the way, you can still send HTML and just wrap a DIV around your pure text with a style="white-space:pre-wrap" along with any font you want which is bad ass as it preserves your return breaks and stuff and you can put <strong> tags or whatever in there and spend way less time.