There aren't a lot of writers trained in the fine points of e-mail writing. As a result, most companies aren't achieving their objectives in terms of sales generated. 

To make things easier, create fill-in-the-blank templates for the main types of e-mail communication you send out. Areas to include in your template:

• Subject lines: Specify the optimal number of words or characters, and provide a few of examples of subject-line approaches that tend to work well.
• Alt-text tags and photo captions: Require that each image (including your company banner) include an alt-text tag in the image itself, as well as an intriguing caption.
• Preview pane: Require that the e-mail's whole message be summed up in one or two sentences at the top of the e-mail, so that it shows through the preview pane.
• Call to action: Specify where the call-to-action message should go (near the top) and how often it should be repeated in the message.
• Sidebars, Johnson boxes, and hotboxes: Create a template to break up information into bite-sized chunks that all appear in the initial screen.

Finally, guide your writers to where their creativity really counts, including:

• The subject line: If it isn't good, no one will open the e-newsletter.
• Your event or Webcast name: It better be compelling, or no one will attend.
• Your headlines and lead-in sentences: If you don't catch readers in the first few seconds of opening your e-mail, you'll lose them as they hit delete and scroll away to view the rest of their inbox.

Source: Tips for Improving E-mail Marketing Performance by Karen Gedney, ClickZ