Effective email marketing in a preview-pane world is all about making your point fast; in the first few inches of your email. Here are eight best practices:

1. Put the most important call to action in the upper left-hand corner, so it can be seen in either horizontal or vertical preview panes. For promotional emails, the offer or "shop now" call to action goes here. For newsletters, the table of contents or "In this issue" teaser goes here.

2. Do not embed copy in images or use single, large images. What happens if your headline, call to action or even the entire email is encapsulated in a graphic? The reader can’t see it at all if that image is blocked. Make your most important points in words, as well as in graphics, and place descriptive copy under each image. Also, always link to a web version of your email with all graphics intact.

3. Use HTML instead of graphics. Many of the issues with image-blocking can be avoided simply by using HTML design choices. HTML background colors, font colors, font tags and font sizes can give you a great look, without the headache.

4. Reduce the size of masthead images and logos and move them out of the upper-left corner.
Those pretty images may brand your email, but they don’t spur the
consumer to click through or convert, and they may not even be seen if
blocked images are a factor. Again, devote the upper-left corner to
driving desired actions.

5. Add text-based email navigation in case images are automatically blocked.
For example, instead of relying solely on a "Shop Now" button that may
never be seen (or clicked), also add a "Shop Now" text link.

6. For big impact, design small. In the early days of email marketing, most templates were 800 pixels wide. Today, 600 pixels wide
is a widely accepted standard, and smart marketers may do well to start
designing even narrower. Even when the user opens an email and views it
in a full window, shrinking real estate can still be a factor. Many
email clients now serve display ads on the right-hand side of the
screen, taking that space away from the message window.

7. Use a third-party rendering tool to avoid surprises.
Rendering tools show you exactly what your message will look like in
all of the most popular email clients so you can improve your design
before you click "Send." It’s smarter than scratching your head
post-launch at puzzlingly low open rates.

8. Use Alt Tags as teaser copy in case images are blocked. A
short, well-written Alt Tag that says something like "Strategies for
improving ROI" where your newsletter banner would be, or "50% off
Wonderful Widget" where a product photo would be can boost your
metrics, but only for Gmail users. All of the other email providers
that block images also block Alt Tags.

Source: iMedia Connection