Choosing the right font [Infographic]

https://blog.hubspot.com/marketing/choosing-fonts-guide

Email Design Guide from MailChimp

http://mailchimp.com/resources/email-design-guide

Improve Email Marketing Using Principles of UX Design

http://isenselabs.com/posts/how-to-improve-email-marketing-using-principles-of-ux-design

The Anatomy of a Perfect Holiday Greetings Email

http://www.rybbon.net/blog/the-anatomy-of-a-perfect-holiday-greetings-email-by-emailmonks/

How to get your emails opened

http://www.jodieadam.com/?p=231

Typographic Patterns In HTML Email Newsletter Design

http://www.smashingmagazine.com/2015/08/typographic-patterns-in-html-newsletter-email-design/

Modern Trends & Design Ideas for Email Newsletters

http://marketblog.envato.com/trends/modern-trends-design-ideas-for-email-newsletters/

The Ultimate Guide to Preview Text Support

https://litmus.com/blog/the-ultimate-guide-to-preview-text-support

Four Creative Email Experiments You Should Try

http://blog.hubspot.com/marketing/email-marketing-experiments