I'm puzzled as to why this is upvoted so highly. It's just a very wide website with a picture and some code on it. "Boilerplate" to me means the legalese at the bottom mandated by corporate lawyers, but I don't see much in the way of boilerplate here.
Is it a template for emails that look like the website? I'd ignore any emails that look like this website, but then I'd never see them, as I don't have HTML email enabled by default, for lots of reasons.
Boilerplate according to Wikipedia is "any text that is or can be reused in new contexts or applications without being changed much from the original."
Coding HTML emails is a very painful task since CSS support is spotty and there are a wide variety of email clients with strange quirks in almost all of them. In order to get things to render reasonably consistently you have to use some really ugly code with tables for layout and inline styles all over the place.
This project collects all (or most) of these hacks into one template that is pretty easy to modify.
Boilerplate may not be the best word... I would have called it "skeleton code" or something along those lines. And the answer to your question is right there in the big box on the site: "This website and its sample code creates a template of sorts, absent of design or layout ...". So, no, it doesn't look like the website or much of anything at all save for a sample line of text, a sample image, and a sample table... all of which you'd delete and replace with the style and content you wish your email to have.
Is it a template for emails that look like the website? I'd ignore any emails that look like this website, but then I'd never see them, as I don't have HTML email enabled by default, for lots of reasons.