Now that HTML is under attack from image-blocking, platforms that don’t properly render it, and aggressive spam filtering that targets non-standard formatting or message size, text e-mail is more important than ever!

But you can’t expect good results if you just slap a text email together and ship it out. Text takes careful design and planning, too. Think lean, clean, and obvious.

Lean: normally, the more links you put in a message, the more avenues to your site you provide readers. In a text message, though, too many URLs can overwhelm the text. Show the most important links. Typically, these are:

• Landing page of the offer or article
• Home page
• Opt-out link (required) and email preferences page (if you have one)
• Contact email address or a link to a contact page

If you typically publish full-length articles in your newsletter,
consider either running just headlines with the first couple paragraphs
or a summary, then link to the article on the site.

Also, create a short table of contents near the top if you have several message elements.

Clean: too much text crammed into a small space turns a text
message into a gray blob. Try the following to help move the reader’s
eye efficiently through the message:

• Use a line length of 50 to 60 characters. In a desktop or Web
  email client, this produces a line long enough to deliver information
  without taxing the eye. If you use a fixed-space typeface such as
  Courier New to compose copy, the line will be about 4 1/2 to 5 inches
  wide.
• Use lots of white space at the top, along the sides, and between
  text blocks. This also helps the eye to focus on the relevant
  information.
• Limit the use of typographic devices (e.g., asterisks, stars, etc.)
  to separate text blocks or add interest. They can trigger spam filters
  tuned to look for oddball punctuation, a typical spammer trick.
  Remember, boldfaced and italicized text won’t show up that way in a
  text message.
• Keep paragraphs four or five lines deep.
• Shorten long tracking URLs you’d ordinarily hide behind keywords or
  buttons in an HTML message. In a text message, they’re ugly and
  distracting and can break if they run over one line.
• Move all standing copy to the end, including the opt-out link,
  contact information, and link to the Web version so it doesn’t
  interfere with the content.
• Test the message before you send. Look for gray copy blocks, broken URLs, awkward layouts, and doubtful entries in the inbox.

Obvious: because your brand or company logo won’t display in
a text message, you must be absolutely clear about who you are to avoid
confusion or be mistaken for a spammer. This starts in the inbox.
Ensure your company or brand, not an email address or department or
employee name, displays prominently in the sender and subject lines.

In the message itself, use a title line to announce the offer or
publication name. You don’t have to worry about copy being blocked they
way images are, but you must still design for a preview pane that
displays only the top 2 to 4 inches of the message.

Source: ClickZ