In another column, I discussed some of the reasons e-mail messages don't always reach their intended recipients.

This column continues with the theme of e-mail delivery not going according to plan, but it focuses on the ways in which content creation and formatting can lead to problems.

History Lesson
When it was originally conceived, e-mail was only capable of handling simple text messages: ASCII text only, with lines no longer than 75 characters.

In due course, extensions were added to enable transport and delivery of more advanced content, including attachments and HTML-formatted messages.

These extensions, known as multipurpose Internet mail extensions (MIME) are, as far as possible, backward compatible with the old text-only system.

However, this transition has not been perfect. Some e-mail browsers still exist that are incapable of handling MIME messages at all, while others might handle attachments but not display HTML. This is the reason for most problems in the presentation of HTML messages.

To a degree, these issues can be minimized either by sending text-only messages or by delivering what's called a multipart or alternative MIME message.

This involves sending a message that includes both a text version and an HTML version. The receiving e-mail client displays only the HTML version if it can or the plain text version if it can't.

As always, there are exceptions to the rule, but this method insures a high success rate and optimizes delivery format for the vast majority of recipients.

Slippery Customers
Most of your recipients are likely to use Microsoft Internet Explorer, Netscape Navigator or variants of these, and both platforms offer predictable, reliable presentation of HTML content.

AOL is a different matter. Until the latest version, 6.0, it used a unique version of e-mail formatting, which has required a separate AOL-specific version for each message. AOL 6.0, however, fully supports HTML.

The current versions of Microsoft Outlook and Outlook Express display HTML correctly, but older versions of Outlook display only the plain text portion of a multipart message.

Finally, e-mail clients such as Pine, and older versions of Outlook, Lotus Notes, and Eudora, incorrectly display HTML or cannot handle it at all.

Enhanced Messages
Much also depends on the bandwidth used by your customers. Those with a cable or a DSL modem are likely to be able to receive rich media-enhanced e-mail messages complete with streaming audio and video or with Flash animations. Those with dial-up modems are less likely to appreciate the degraded quality of their low-bandwidth versions of rich content.

Other issues arise when you attempt to deliver messages in foreign languages or include 8-bit characters such as the copyright symbol. Such 8-bit characters require an added layer -- and subsequent unpredictability -- of message encoding and decoding by the recipient's e-mail client software.

Use of JavaScript within an HTML message can cause problems, too.

Because JavaScript is a common method for propagating e-mail-borne viruses, many e-mail servers are configured automatically to reject any messages containing it. Others might attempt to "defang" the JavaScript, resulting in the message not being delivered as you intended.

Weakest Link
Your customers might complain that links within the message do not work. This can happen for a number of reasons:

  • The URL link within the message might simply be wrong.
  • The linked Web page might not yet have been uploaded to the Web server or might have been moved, resulting in a "404 Not Found" error.
  • If a URL within a plain text message is too long, it might be wrapped onto a second line by the e-mail client software and not work correctly.
  • Sometimes, due to encoding that occurred during message relay via the Internet and improper decoding on receipt, your links terminate with the additional characters "=20" and do not work.

It should be clear by now that you can never realistically expect 100% successful delivery of any e-mail campaign.

But the good news is that you will get an accurate picture of where the errors occurred, and you can arm your customer service staff to handle some of the questions that will inevitably arise.

Although it can cause an unexpected level of novel -- and unpredictable -- customer inquiries, you should view this extra accountability as an asset. After all, when was the last time the U.S. Postal Service provided a blow-by-blow account of its failed deliveries and gave you the opportunity to improve the customer experience?

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