How to Pass Through the Gmail Spam Filter to Land in Customer’s Inbox

ByMohamed Natheem


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Gmail has many spam filter barriers which are hard to pass by. It uses machine learning and AI to decide whether to send an email to the spam folder or inbox.

Google in its security blog stated that their spam filter mechanisms prevent more than 10 million unsafe or unwanted emails from reaching the users.

In this guide, you’re going to learn about precautions you can take to minimize the chances of being blocked by the Gmail spam filters.

Table of contents

How does the Gmail spam filter work?

Like any other email client, Gmail has a filter to decide whether an email is spam or not. It'll send your email straight to the spam folder if it matches too many of those predefined criteria such as,

  • Sending emails to unengaged users

  • Blacklisted email/IP address

  • Sending malicious links inside the email

  • Using spam trigger words in body and subject lines

  • Poor sender reputation

  • Sending unsolicited emails

  • Mixing different types of content in the same messages

  • Impersonating other domains without consent, etc.

Bjorn Grubelich, product manager for Gmail, says that Google uses machine learning models to block more than 99.9 percent of spam and phishing emails from reaching Gmail users.

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How to pass through the Gmail spam filter?

Gmail does not reveal the criteria used in its filters, but there are some precautions you can take to minimize the probability of ending up in the spam folder.

1. Ask users to add you to their contact list

"Messages that have a From address in the recipient's contacts list are less likely to be marked as spam." - Google.

Ask your customers to add your email to their contact list. If your customers do that, it'll send an indication to Google that you are of importance to them, so your emails are less likely to end up in the spam folder.

2. Get permission from your customers

You should get permission from your customers where they opt-in to your email list and agree to receive your emails.

You can do that by offering a lead magnet and asking them to exchange their emails addresses and tick a checkbox that says something like "I agree to receive marketing emails from Mailmodo."

You can either use a single opt-in or double opt-in method to achieve this objective.

3. Don’t use a purchased email list

Many people think about buying an email list to build up their audience quickly. However, this will send your emails to the spam folder because recipients on that list are more likely to mark your unsolicited emails as spam since they don't recognize you.

Also, you’ll be marked as spam by mailbox providers and other organizations because they use pristine spam traps to identify people who buy an email list. All organizations expect you to build your list in an authentic way and don’t buy a list. So it’s best to avoid purchasing a list.

4. Make it easy to unsubscribe

Add an unsubscribe link in your emails on which the recipients can click to unsubscribe from your email list. And please stop sending them emails after they’ve unsubscribed, or they will mark you as spam.

Not doing so will definitely hurt your deliverability, domain reputation, the overall success of your email marketing campaign. So respect your customers' decisions and unsubscribe them from your list if they want you to.

5. Don't send emails to unengaged subscribers

If your emails sit in your subscribers' inboxes without being opened, the Gmail spam filter will consider your future emails spam. You might create a sunset policy and a suppression list to manage these unengaged users.

One of the best things you can do is track these unengaged users with your email service provider. You can send them a reminder asking why they haven’t engaged with your emails. Then, ask them if you can do something else for them. If they remain unengaged for a significant time even after the initial ask, it is best to avoid them altogether.

These people find you irrelevant and won’t ever do business with you. So instead, focus your time and energy on people who are engaging and value your content.

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6. Use spam checkers

Spam checkers are online tools that will check your email against parameters like a spam assassin score, DKIM, and SPF. Then they’ll generate a report that shows how spam filters rate your emails.

You can use a spam checker such as Experte or Mailgenius to generate the report.

Related guide: What Is SpamAssassin and How to Avoid It

7. Verify the email content

Gmail's spam filter might block emails with content that doesn't look legitimate. Proofread your content to check whether your content is relevant to your audience, doesn't contain too many images and links, less text, and doesn't use spam trigger words.

8. Set up email authentication

Email authentication helps email clients verify that the email comes from a legitimate domain and is allowed to land in the inbox.

SPF, DKIM, and DMARC are the email authentication protocols used to authenticate incoming emails in the mail server. For senders using Mailmodo, we assist you in setting up the authentication protocols to escape from the Gmail spam filter.

9. Monitor sender reputation

A sender reputation score is a crucial metric that affects email deliverability. By monitoring and improving the email sender's reputation, you can bypass the spam filters and land in the customers' inboxes.

You can use sender reputation tools like, Google Postmaster Tools, or SpamAssassin to check your score.

10. Whitelist your email

The last step you can do to keep your email from ending up in the spam folder is to ask your subscribers to whitelist it. A whitelisted email will always be delivered to Gmail's main inbox. If your email is on the whitelist, Gmail will recognize that your domain is authentic and work to prevent your emails from ending up in the spam bin.

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Wrapping up

If you don’t have the intention to spam, you don’t have to worry too much about ending up in the spam folder. But taking precautions is never bad. As simple as getting permission from your customers can significantly improve your deliverability.

What you should do next

Hey there, thanks for reading till the end. Here are 3 ways we can help you grow your business:

  1. Talk to an email expert. Need someone to take your email marketing to the next level? Mailmodo’s experts are here for you. Schedule a 30-minute email consultation. Don’t worry, it’s on the house. Book a meet here.

  2. Send emails that bring higher conversions. Mailmodo is an ESP that helps you to create and send app-like interactive emails with forms, carts, calendars, games, and other widgets for higher conversions. Get started for free.

  3. Get smarter with our email resources. Explore all our knowledge base here and learn about email marketing, marketing strategies, best practices, growth hacks, case studies, templates, and more. Access guides here.

What should you do next?

Thanks for reading till the end. Here are 3 ways we can help you grow your business:


Get smarter with our email resources

Explore our email marketing guides, ebooks and other resources to master email marketing.


Do better email marketing with Mailmodo

Send app-like interactive emails with forms, carts, calendars, games, etc. to boost email ROI.


Talk to an email expert

Get a 30-min. free email consultation with a Mailmodo expert to optimize your email marketing.

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