A Different Animal
It has been a while since I have churned out HTML emails. They are a different animal than landing pages to be sure. Years ago, I created a generic master email template for the entire art department to pull from. It was a simple HTML file they could make their own. I hear they have made some tweaks to better fit their needs, but still pull or refer to it as a resource even today.
Master Email Template
Here was some simple emails I knocked out a few years back. I added comments for cut and paste. Added top media queries for responsive, but personally I usually used fluid responsive so it could work in all devices. The media queries will get stripped out from some email clients. Fluid responsive is more reliable as it is just elastic or will just wrap down naturally.
Other Emails
Here are some emails I did for Pearson Online Learning many years ago. These were entirely custom so took longer to build. I did use more media queries back then but tried to stick to fluid responsive as a first choice.
Here is another back from the Pearson era. Again all custom builds so they took longer than using a master template. Looking back, alot of time was spent developing what seemed almost an email newsletter. Most people, me included, just was to see a simple great offer email that connects in 1-2 seconds. Nothing more. Usually people have one finger on the delete button as they scan their emails. I would recommend keeping it simple and to the point.
What Works Best
Don't overbuild; most folks just want a clear offer fast. Short headlines, clear CTAs, and easy layouts beat anything fancy. Build flexible emails that hold up across all clients. Simple, fast, reliable emails convert better than fancy ones.