A summary of relevant elements from the outline:
Always use third-party email providers. They may be expensive but it is much better than trying to do things in-house. If nothing else, these providers won’t get you blocked/blacklisted by the spam monitors. They also offer analytics to let you track your mail campaign that home-grown systems do not have.
Make your HTML templates simple and unobstructive. Remember that most people view with images off, so look at your email that way before you send it and make sure that it doesn’t lose meaning. Use clear and concise alt tags!
Your email campaign should have a look and feel that corresponds to your public web site. They don’t need to be identical, but that visual similarity helps to reinforce your brand and your campaign points.
Use table structure to create your outlines, not CSS. Email clients haven’t caught up with browsers in how they render things, so don’t be a standards-snob. Many will not support the paragraph <p> tag either, so it is best to stick with divs and tables.
Always test your email templates. Using Gmail, Yahoo, AOL, and HotMail should cover the majority of the public mail clients. You can also consult http://email-standards.org or any similar blog that tracks supported features of the various mail readers.
Content is king. Keep your call to action short and concise. Ideally your email should be centered around one topic or idea. Keep content short – “Don’t make me scroll.” Long newsletters are particularly burdensome.
Use descriptive subject lines – tell us what’s inside the email. Users will often decide how much attention to give the email (even once opened) by what they first read in the subject.
Assuming you are using HTML mail, use the HTML. Link your URLs, don’t write them out or put them afterward in parentheses. You should never have visible URLs unless you expect the email to be printed.