Quick HTML Tips to Improve Email Deliverability

By Bennett Olson

December 8, 2009 — There are many variables that affect email deliverability, but one that’s often overlooked is the email’s HTML code. Seemingly innocuous things can severely impact whether your email will get to the inbox or be seen as spam. In this light, we’ve assembled simple tips you can use to improve your email templates and increase deliverability.

• Make sure your HTML is very “clean”. WYSIWYGs are notorious for putting in a lot of extraneous code that’s invisible to the user. Though this won’t affect the way your email looks, spam filters notice these unnecessary elements and assume the email was created by a spammer that doesn’t know HTML.

• Be careful not to overemphasize your text. Using bright colors, capitalizing multiple phrases or using a lot of exclamation points increases the probability that your email will be seen as junk.

• Give your email template a title or delete the title tags altogether. Messages that have nothing between <TITLE> and </TITLE> are often seen as spam.

• Don’t use hex-encoded domains in URLs (e.g. substituting the code "%20" for a space in a URL). This can get your email blocked or sent to the bulk folder.

• Avoid using large images in your email; this is what spammers use.

• Don’t put any code beneath the close HTML tag. Many marketers put their tracking pixel here so that it doesn’t interfere with the main content. Aesthetically this makes sense, but it increases the chances of your message being flagged as spam.

• Include a text version of your message along with the HTML. You need to use an ESP (Like StreamSend) to accomplish this, but it’s an important criterion for many spam filters.

• Only test your email with real copy. Spam filters get very suspicious of emails with “lorem ipsum” or duplicate text (i.e. pasting the same paragraph over and over).

• Validate your email to address syntax errors. Common errors, such as using <a/> instead of </a>, have been known to trigger spam filters. The WC3 has a free validator that is very effective at identifying these problems (http://validator.w3.org/).

These tips are by no means all-encompassing, but they will help. There are so many spam filters, each with a different way of classifying spam, that there is no such thing as a perfect email template…and there never will be.