A common email marketing misconception is email is filtered because it contains words such as "free" in the subject line or body. By itself, that won’t get your email filtered. Though certain content combinations may get a message filtered, ISPs may be trapping your legitimate email for infractions you rarely pay attention to.
Take HTML code. Using outdated or incorrect code is a major reason why email to domains such as MSN/Hotmail and AOL are blocked or delivered to bulk or junk mail folders.
You may think you don’t have to worry about this. Your email may render correctly and look just fine to you. Wrong! Pivotal Veracity, a delivery-monitoring service provider, estimates nearly 100 percent of all HTML email doesn’t comply with World Wide Web Consortium (W3C) standards.
Because each ISP handles email differently, messages that get past the filters at one destination may be filtered or entirely blocked at another. Why are some ISPs so concerned about HTML code? You can thank spammers, of course. HTML syntax and format errors are common tricks spammers use to foil standard content filters.
Some W3C infractions are minor and won’t cause email to be filtered. An example is not using "alt" tags, which describe the content in an image tag. Many other innocuous-appearing coding errors or tricks may send your email straight to the bulk folder.
Pivotal Veracity recently tested hundreds of HTML email messages to see whether they landed in the inbox or the bulk folder, or were blocked outright. They came up with these surprising results:
AOL’s HTML Validator
While conducting tests for our clients several months ago, we discovered a new AOL email filter that scans incoming messages for HTML syntax and format errors. If it detected invalid HTML, it rejected the message. AOL even created a special bounce code it used when rejecting a message for this reason.
Common errors, such as using "" to close an HTML tag instead of the "," could trigger the filter. Pivotal Veracity’s recent testing suggests AOL may no longer be applying this filter. The bottom line is check your code carefully and correct any syntax errors.
Minimizing HTML Filtering Problems
How do you minimize or eliminate HTML filtering problems at ISPs? A few suggestions:
In a future column, we’ll walk you through an actual diagnosis of code problems and show you how to resolve them. Stay tuned.
Till then, keep on deliverin’.
Want more email marketing information? ClickZ E-Mail Reference is an archive of all our email columns, organized by topic.
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As director of ISP relations and delivery, Kirill Popov creates and enforces strict usage and anti-spam policies, maintains ISP and community relations, and oversees all abuse and policy investigations and inquiries for EmailLabs clients. Kirill works with clients on best practices, content, design, and list hygiene to minimize potential delivery issues. He's a registered member of the SpamCon foundation and representsEmailLabs on AIM's Council for Responsible E-Mail.
Loren McDonald is vice president of marketing at e-mail marketing automation company EmailLabs, overseeing corporate marketing activities and client consulting services. He has 20 years experience in marketing, consulting and strategic planning. Earlier, Loren was founder and president of Intevation, an e-marketing services firm specializing in e-mail and SEM. He's held executive marketing positions at companies including USWeb/CKS (marchFIRST), NetStruxr, and Arthur Andersen.
December 12, 2013
1:00pm ET / 10:00am PT