10 Tips To Avoid Email Spam Filters and Reach Your Subscribers’ Inbox

Have you ever wondered why your open rate suddenly drops into 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 spam filter?

A spam filter generally uses technologies like artificial intelligence and machine learning to detect unsolicited, unwanted, virus-infected messages (usually known as spam) and prevent them from reaching the primary inbox.

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. Since the spam-identified emails are delivered, the diminished access to them usually affects your overall email open rate.

The spam filter evaluates one or more factors to determine if the email should go to the primary inbox or the junk folder, including:

• Subject lines that appear false or suspicious
• Senders with blacklisted IP addresses
• Spam-related words or phrases
• Input from recipients who define rules that eliminate spam emails from the others

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

1. Provide double opt-in

Use a double opt-in form. Visitors who fill out a subscription form must confirm their registration through a separate email.

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When people take the extra step to confirm their subscription, they are less likely to report your emails as spam.

As a bonus, you also get more accurate email addresses, improving the quality of your list in the long term.

2. Maintain your IP reputation

Your IP address reputation is a huge factor in email deliverability. 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.

You should warm up the IP address by sending a low volume of email at first and increase the quantity over time.

Building your IP reputation slowly helps email service providers better understand your sending behaviors, list accuracy, and how subscribers respond to the emails. If they’re positive, email service providers are more likely to deliver them.

3. Avoid trigger words or misleading subject lines

Your words can trigger spam filters no matter what your original intention was. Phrases like “earn extra cash” or “increase sales” often get caught by email filters. Pay careful attention to every word and phrase you use, from the subject line to the body copy.

A 2016 study from Litmus found 54% of those surveyed reported being deceived by misleading subject lines to open a promotional email. When deceived, recipients also are more likely to flag your emails for the spam folder.

Your best bet is to craft strong headlines and sidestep spam words.

Here are some no-no words from HubSpot:

4. Ask your subscribers to add you

When they sign up, ask your subscribers to add your email address in their approved contact list (i.e., primary tab).

If they do add you to their contacts, it helps them and other subscribers see your emails. Including you on their OK-to-receive list, a trust signal automatically gets sent to service providers like Gmail or Apple Mail, which reduces your email spam score.

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 value-packed content

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

Email service providers like Gmail look closely at the engagement your emails receive from your subscribers. If your emails have low open and read rates, subsequent outreach might get sent to the promotions tab or even end up in their junk folders.

Personalization can be helpful in creating a wow perception. In this example, Mindvalley personalizes the intro and creates a sense of urgency and high impact:

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 mean it takes longer to download the email, they often lead the email directly to a bounce or the spam folder.

Instead, send subscribers to a landing page with that content by including a link or call-to-action button in the email like Netflix does here:

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7. Follow the law

Most countries have anti-spam laws (CAN-SPAM ACT, GDPR, CASL, etc.) to protect their residents’ data from spammers.

If you have U.S. subscribers, compliance with the CAN-SPAM ACT should be your top priority. Among the requirements:

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

Look to each country to determine its specific anti-spam guidelines and laws.

8. Use proper 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 only image-based content. Mailchimp advises a ratio of 80% text to 20% images in an email.

You also should follow these other best image-related practices:

• Provide alt text for each uploaded image.
• Limit images to no more than three.
• Test emails with images on different clients (like Gmail and Yahoo) to see how it translates before sending them to your entire list.

9. Avoid inactive subscribers

Some subscribers will be inactive no matter how often you reach out to their inbox. It may happen because they changed their email address as 31% do in a 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 and your emails are less likely to get flagged by spam filters.

We suggest adjusting your send frequency based on their activity before you delete their email addresses:

• After 30 days, send mid-frequency emails.
• After 60 days, send low-frequency emails.
• After120 days, send a re-engagement campaign.

• If they still do not engage, remove (or sunset) them.

10. Use email checkers for spam scores

At this stage, you have some good ideas on what you should do.

But if you still have some issues with these spam filters, spam testing should be the last sure thing you can do to beat the spambots.

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

• My company Omnisend offers a subject line testers tool that evaluates multiple criteria, including spam potential.
• Mail-Tester rates your email on a spam score of zero to 10. It also details what’s good and what’s not so you know what to fix.

• Glockapps tests your email copy and gives it a score up to 100 at no charge. If you provide your email address, they send an in-depth spam test report with more details on improvement opportunities.

Reach your subscribers’ inboxes

Improving your open rate is an ongoing process but avoiding spam filters is a fantastic 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.

All tools mentioned in the article are identified by the author. If you have a tool to suggest, please feel free to add it in the comments.

Cover image by Joseph Kalinowski/Content Marketing Institute