Avoiding The Spam Filter

May 27, 2014

Designing and coding email templates can be tricky because there are many different email providers and many devices on which people read their email. What makes email templates particularly different to designing web pages is the battle to stay out of the spam filter!

A surprisingly large amount of legitimate email routinely goes undelivered because ISPs incorrectly detect it as spam. Here are my top tips to help make sure yours aren’t some of them.

Content: Avoid using any spam trigger words in the content of your emails otherwise they can end up in a spam folder. Make sure your messages do not have spelling or grammatical errors as any such errors increase your chance of being flagged as spam. Place your company name and contact details prominently in the email to make it clear that the message is from a legitimate source.

Link click tracking: If your mailing application alters links in order to track clicks, do not use the original URL as the link anchor text as there will then be a mismatch between the location of the link and the text of the link. Spam filters can think that this is a phishing attack.

Design: Get your emails designed by somebody who knows how spam filters work. Subtle differences such as the colour of the text can make the difference between an email message being scored as spam or not.

Code: Most email programs support HTML emails, but even so a plain text version should be included as well. Sending HTML-only emails is a common reason for ending up in the spam folder. Make sure that HTML is well formatted and that all the tags are valid and properly closed. HTML errors are a common cause of emails getting marked as spam. If you aren’t proficient in checking your HTML code, use a professional and get it done properly. Do not try to save a Microsoft Word document as HTML as this is notorious for producing bad code.

Images: Email software often turns off images as a security measure, so you don’t want to rely on communicating important information with an image. You certainly shouldn’t send any image-only emails as these are almost always marked as spam. Use images sparingly and test that the email still conveys its message if the images do not load. Images should not be embedded in the email, but should be stored on a webserver and linked to. The images should have an alt description added so that the recipient will be able to see what they are missing and will opt to download the full message.

Attachments: Do not attach any large files or any executable file type (.exe .zip or .swf). These file types are often considered malicious.

Unsubscribe links: All email providers now check for the presence of an unsubscribe link. Even though it doesn’t make sense to have these links in a transactional email, it can make a difference to your message getting to an inbox or being marked as spam.

Testing: Test against a selection of spam filters to make sure the email gets through before you send it out to the entire mailing list.

Maintain a clean mailing list: If messages you have sent before have not been opened or have been reported as spam, then further emails will be less likely to make it to the inbox. Remove subscribers who do not open your emails. Read this blog post for more about maintaining your mailing list.

Remember that email isn’t just about marketing. Order confirmations, friend requests, password resets, shipping notifications, invoices, privacy updates are all communications regularly sent via email. Did you know you don’t always get a bounce notification if your email isn’t delivered? A bounce message is sent if an email account is no longer active or the mailbox is temporarily full. However, ISPs can block or put a message in the junk folder without sending you any notification. Falling into a spam filter usually goes unnoticed and the first you will know of it will be when your customers complain.