I first started working on emails when I was working at Centcom, Ltd., the advertising arm for the American Chemical Society.
Every other week I would send either an email or a fax to the many chemical companies that advertised in their key publication, Chemical & Engineering News. We used ACT to schedule and send the emails and faxes, and were able to track the results. 
Email has changed a lot since then. More recently, when I was working at CRC Press, I was initially involved in proofing the emails we sent out on our newly published books.
As the program grew, it became clear that we needed a process so that we could save time and train and get others involved.So I created a manual that documented many
different parts of the email program, inluding internal and external list gathering, proofing and testing the emails prior to distribution, and tracking the results after we hit send in MagnetMail.
I also created a checklist that we used in the proofing process which also served as documentation that we had covered all of our bases including testing promo codes and URLs, and checked grammar and spelling, etc.