July 9, 2014

Avoiding Spam Filters


You could spend countless hours creating the perfect email marketing campaign to send to your customers. However, without taking some basic steps to keep your spam score low, spam filters could put a big dent in your deliverability. Earlier we outlined some simple steps to increase the success rate of your emails, but avoiding spam filters can be a challenge. Let’s take a look at these helpful tips to preventing your email from being marked as spam:

1. Copy

There are many different triggers that you should avoid using in the body or subject line of your emails.

  • Avoid excessive keywords – While you may be used to writing keyword-heavy content, excessive keywords are common reason emails get flagged as spam. Unlike search engine optimization (SEO), optimizing keywords in your emails offer little benefit.
  • Avoid using excessive exclamation points or punctuation.
  • Avoid using words like free, no-obligation, or guarantee in your subject lines or content. Instead, we suggest using images containing these words in moderation as bigger, more attractive calls to action.
  • Avoid use excessive capitalization or all caps text.
  • Utilize the spam score tools provided by your ESP to analyze your content. These tools will help with fixing issues before you send a campaign. If your ESP does not have a spam tester, try a free one like Mail Tester.
Mail Tester makes it easy to avoid spam filters

Mail Tester in action

Also, don’t forget to use spell check. Even if you use the right copy misspellings are a flag for spam filters as well.

2. Content

Here are some practical tips for developing your content to avoid spam filters:

  • Never attempt to include forms, videos, flash, or javascript. If possible, also try to avoid attachments.
  • Aim for a 400 or 500 pixel width on your email container. This will make your email better optimized for mobile devices. If you want to take advantage of desktop email clients that can comfortably display 600 pixels or more, we recommend using a responsive email template framework like Zurb Ink.
  • Your image to text ratio is another thing to look out for. For best results, aim for a 60/40 text to image ratio.
  • Keep your images short and sweet. We recommend limiting your emails to 3 or 4 images and keeping the file size 20 kilobytes or lower.
  • If your email is light on content, try adding more text to the footer of the email and add additional ALT text to all of your images.
  • If applicable, focus on styling your text to match the email design. Replacing images that could be text is an easy way to improve your text to image ratio.

3. Recipients

Always use your own lists. Even if a consumer double opts in to a list you purchase, they still aren’t likely to recognize where your email came from. Buying lists significantly increases the probability of recipients marking your email as spam.

It’s also important to regularly clean and purge your mailing lists. If you’re not ready to remove address altogether, we recommend sending a re-engagement email to get your customers to opt in again.

Author: Alex Griffis

Alex Griffis is the VP of Product (a product geek) at 250ok, where he focuses on product design and improving our customer experiences.

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