A feature of many mailing programs is the ability to auto-detect the recipient’s email client and then send email that meets the recipient’s capacity to render HTML. In some respects the auto-detect feature is a legacy hangover from the days of text-only email clients. We didn’t all wake up one morning to an email client that was fully capable of displaying complicated CSS driven layouts and pretty graphics. The update was a gradual process and as people adopted more robust email clients marketers began to send more robust emails with increasingly complicated code.
Today we ooh and aah at the beautiful emails our design and production departments generate in hopes of garnering clicks and conversions, but a brief look under the hood reveals a glaring hole caused by some auto-detect systems: sending only one part of a Multi-Part MIME message may cause your email to be filtered as spam.
MIME (Multi Purpose Internet Mail Extensions) extends email by supporting message bodies with multiple sections and varied encodings among other features. This means that you can send both an HTML portion and a TEXT portion in the same message. The recipient’s email client will render the one it is a) capable of rendering and, b) the portion the recipient prefers to see. Contrary to popular belief, not every single person in the world wants to see HTML in their email.
So what’s the problem you ask? The problem is simple: marketers are sending Multi-Part MIME messages but omitting the TEXT part of the MIME. When you send a Multi-Part MIME you are declaring that you are sending more than 1 MIME part—leaving out the TEXT part, or in the rare case that you only send the TEXT part minus the HTML you are in essence breaking the standard.
By not sending both parts of the MIME you run the danger of having your messages flagged by a heuristic filter that specifically checks valid MIME headers that include TEXT & HTML. SpamAssassin score increases, due to triggering this rule, could be as high as 1.672! When you consider that your total heuristic spam score must be under a 5 to deliver to certain ISPs this single rule alone could put you over the top, leaving your carefully crafted email in the spam folder!
Following best practices and technical specs will ultimately help you achieve higher ROI by helping more of your email reach the inbox. Taking short cuts like omitting necessary MIME portions in the hopes of minimally shrinking your message size will probably hurt you more than anything else. Yes, it takes a bit more time to craft the text portion, but look at it this way—you are casting a wider net in hopes of reaching more of your fans and customers that really do want to read your message, even if they’re still using Pine or some other antique mail client.
Last 5 posts by Len Shneyder
- Job Opening - Product Manager EMM - May 12th, 2011
- The New Mail.com Webmail Client - March 30th, 2011
- The New New Yahoo! Mail Beta - March 18th, 2011
- Mail.com Bulk Foldering 90% of Inbound Mail - February 24th, 2011
- HTTP, HTTPS, Gmail, IE – INCONCEIVABLE! - January 6th, 2011
