10 Tips to Avoid Email Spam Filters

Ever wonder why your open rate suddenly drops to the single digits.

It could be the result of updated filters now sending your brand’s emails to your subscribers’ spam folders. But you don’t have to surrender to those spam filters.

Here’s what you need to know to help your emails avoid those troublemakers that dump the good with the bad in spam filters.

What is an email filter for spam?

A spam filter is a system that uses machine learning and artificial intelligence to detect spam and virus-infected messages.

While it affects where the email goes inside the recipient’s system, it does not impact your email delivery rate, which is based on how many emails are delivered. Your overall email open rates will be affected by the reduced access to spam-identified emails.

#Email in spam folders counts as delivered so they likely hurt your open rates, says @bernardgmeyer via @CMIContent. Click To Tweet

The spam filter looks at one or more factors in order to determine if an email should be forwarded to the primary or junk folder.

  • Subject lines that seem suspicious or false
  • Blacklisted IP addresses for senders
  • Spam-related words and phrases
  • Recipients may provide input that will help to define rules to remove spam emails from the rest of the world.

You can’t totally escape spam filters, but you can follow these 10 steps to lower your spam scores and enhance email deliverability.

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1. Provide double opt-in

Double opt-in forms are recommended. Visitors who complete a subscription form need to confirm their registration via a separate email.

Image source

People who confirm their subscription are less likely to report your email as spam if they take the extra step.

A double opt-in means subscribers are less likely to report your #content as spam, says @bernardgmeyer via @CMIContent. #EmailMarketing Click To Tweet

You also get more accurate email addresses, which will improve the quality of your long-term list.

2. Keep your IP reputation intact

Email delivery is affected by the reputation of your IP address. If you send an email campaign from a newly created IP address to a high volume of recipients, email service providers like Gmail, Apple Mail, and Yahoo may hesitate to send your email to the recipient’s inbox.

It is important to start by sending low volumes of emails at first, and then increase the number over time.

Slowly building your IP reputation helps email service providers better understand how you send emails, your list accuracy, and how subscribers react to them. If they’re positive, email service providers are more likely to deliver them.

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3. Avoid using trigger words and misleading subject lines

No matter what your original intent, spam filters can be triggered by your words. Phrases like “earn extra cash” or “increase sales” often get caught by email filters. Pay attention to every word and phrase that you use, from your subject line to your body copy.

Litmus conducted a 2016 study and found that 54% of respondents reported being deceived to open promotional emails. If recipients are deceived, they are more likely to flag your email for the spam folder.

It is best to create strong headlines and avoid spam words.

Here are some HubSpot no words:

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4. Ask your subscribers for their support

Ask your subscribers when they sign up to include your email address in their approved contacts list (i.e., primary tab).

If they do add your name to their contacts, it will help them and other subscribers to see your email. By including you on their OK–to-receive lists, a trust signal is automatically sent to service providers like Apple Mail or Gmail, which lowers your email spam score.

Subscribers who add your #email to their sender lists automatically signal trust to email service providers, says @bernardgmeyer via @CMIContent. #EmailMarketing Click To Tweet

Here’s an example of the request from Ann Handley’s Total Annarchy newsletter. She includes it – and instructions on how to do it – in her welcome message:

5. Send valuable content

You’ve taken steps so your content is more likely to appear in the inbox, but the job isn’t done. You must now wow your subscribers each time they open your email.

Gmail, an email service provider, closely examines the engagement of your subscribers. If your emails have low open or read rates, any subsequent outreach might be sent to the promotions tab.

Personalization can help create a wow impression. Mindvalley personalizes this intro to create a sense of urgency.

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6. Forego attachments

If you’re inclined to attach a document with more information, a special coupon, etc., don’t do it. Attachments not only slow down the process of downloading the email but also lead to bounces or spam folders.

If you’re inclined to attach a document with more information such as a special coupon, don’t do it, says @bernardgmeyer via @CMIContent. #EmailMarketing Click To Tweet

Instead, send subscribers directly to the landing page by including a link or call to action button in your email. This is what Netflix does here.

Image source

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7. Follow the law

Many countries have anti-spam laws. to protect their residents’ data from spammers.

Compliance with the CANSPAM ACT should be your number one priority if you have U.S. subscribers. Here are some of the requirements:

  • Don’t use any false or misleading sender names. The sender should be an actual person from your team and registered to valid domain names.
  • Please provide your postal address. It can be your current street or a registered U.S. Post Office Box. It can be your current street address, a registered post office box with the U.S., or a private mailbox.
  • Respect opt-out requests promptly. When subscribers tell you that they don’t want to receive more emails from you, remove them.

For anti-spam laws and guidelines, look to each country.

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8. Use the right text and image ratio

Spam filters block image-heavy content. Even if they don’t, some recipients use email providers that disable images by default.

Avoid using image-based content. Mailchimp suggests that emails contain 80% text and 20% images.

[email protected] advises a ratio of 80% text to 20% images in an #email, says @bernardgmeyer via @CMIContent. #EmailMarketing Click To Tweet

These are the best image-related practices that you should also follow

  • Add alt text to each image.
  • Limit images to three.
  • Before you send emails with images to your entire list, test it on different clients (such as Gmail or Yahoo).

9. 9.

Some subscribers will not respond to you no matter how many times they are contacted. It could be that they have changed their email address, which is what 31% of subscribers do every year. Or they may have lost interest in your content because their needs have changed or they don’t have time to consume them.

Treat subscribers who haven’t opened your emails in at least six months as an inactive subscriber. Your list will be cleaner. Also, your emails will not be flagged as spam.

Before you delete their emails, we suggest that you adjust your send frequency according to their activity.

  • Send mid-frequency email after 30 days
  • After 60 days, you can send low-frequency email.
  • After 120 days, send out a reengagement campaign.
  • If they don’t engage, remove them (or sunset).


10. Email checkers are useful for reducing spam scores

You have some ideas at this stage.

If you have any issues with the spam filters, spam testing is the last thing you should do to defeat the spambots.

Here are a couple of tools that will help you improve your email spam score based on the mistakes you’re making:

  • Omnisend provides a subject-line testers tool for evaluating multiple criteria, including spam potential.
  • Mail-TesterYour email is rated on a spam score from zero to 10. It also details what’s good and what’s not so you know what to fix.

  • Glockapps checks your email copy and gives it an instant score of up to 100. They will send you a detailed spam test report with additional details and improvement suggestions if you provide your email address.

Reach your subscribers’ inboxes

While improving your open rate is a continuous process, avoiding spam filters is a great start. By following these 10 steps, you are more likely to get emails out of the spam folder and to the top of your subscribers’ inboxes.

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The author has identified all tools mentioned in this article. If you have a suggestion for a tool, please leave it in the comments.

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Cover image by Joseph Kalinowski/Content Marketing Institute