Marketing Sherpa

The Marketing Sherpa provides a fantastic source of info for all things communication. Their email marketing surveys also contain great info on Transactional Email

"All things Marketing"

Mailchimp

See what the folks at Mailchimp think. The rulers of all email products fronted by a monkey

They even provide a great library of starting email templates that you can use as the foundation for creating your own great email.

"They made Mandrill"

Email Expert

I guess anyone that calls themselves the "email expert" must know something. These 14 best practice tips are pretty ubiquitous

"Get on board"