How to Keep Your Emails out of SPAM Filters

Deliverability is the first hurdle in successful email marketing. It may surprise you to learn that even if you have your customer’s permission to send emails, spam filters can block 10%-20% of those emails. While all spam filters work basically the same way – it’s a point-based system – there is no industry standard. What this means to email marketers is that what gets through one system may not get through another. The rules can change daily with no consistency over email platforms.

There are best practices, however, that will give your emails the highest chance of reaching their targets. Spam filters assign points for various aspects of the email. If the email scores at a specific point or higher, it is blocked from delivery.

The number one factor that determines deliverability is the sender’s reputation. This is why it is best to use a reputable commercial email service. These services invest in minimizing their bounce rates and maximizing their open rates – two factors that reduce the number of spam points they accumulate. Another piece of the sender profile is the authentication of the originating domain name and IP address. All spam filters check these to determine authenticity.

Spam Assassin is an open-source spam detection program that provides a helpful list of things to avoid when creating and sending email. Here are some common-sense rules based on what spam filters are looking at:

  • Formatting – stay away from using all caps, multiple colors, special characters and too many exclamation points.
  • Images – don’t use too many or one single large image. Balance text and graphics.
  • Code – beware of sloppy HTML code that has open tags or is generated by Microsoft Word. Make sure that emails are also available in text-only format.
  • Language – avoid spam trigger words like money back, act now, limited time, coupons, click now, and open immediately. Make sure there are no misspelled words or typos.
  • Links – Make sure your links aren’t broken and avoid link shortener programs like, and Tiny URLs.
  • Subject line – should be relevant and engaging and NEVER IN ALL CAPS.
  • “To” name – instead of [email protected] or [email protected], using Nancy’s full name will help keep your email out of Nancy’s spam filter.

Make sure to include a clear and easy opt-out option. Not only is this a requirement of the CAN-SPAM law but it also tends to reduce spam complaints. Including a physical address is also required by law and not including an address is a spam trigger.

Two overarching practices will stand you in good stead with email deliverability: 1) use a reputable deployment service and 2) send relevant content with engaging subject lines.

Your initial copy should mimic the style of the email or ad copy for two reasons: 1) so visitors feel like they are in the right place and 2) to reinforce your call to action. Make it easy to read. No need to use complex terminology and complex sentences. Stay on point to lead the reader through all the reasons why they should respond. Use uneven paragraphs and even single sentences as paragraphs as they keep the reader engaged.

The Agile Education Marketing team stands ready to work with you to design your emails for maximum deliverability. Find out more here.

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