When launching an email marketing campaign, even the most successful companies face the threat of spam filtering. Modern spam filters are constantly being improved, so every email marketer should keep pace with these changes. Moreover, do not forget about your subscribers who can mark your messages as spam even after receiving.

This article will help to deal with the main reasons for falling under the filters. You will learn how to avoid emails going to spam.

How Do Spam Filters Work?

First, let’s find out who creates spam filters.

In the fight against spammers are involved:

  • Internet Service Providers. They develop rules to screen out suspicious activity on the network. Their security measures applied to spammers as well. For example, ISPs collect DNS-based Blacklists, by which they automatically check senders. If the system finds the IP in the Blacklist, it does not allow the incoming messages from this address.
  • Email Service Providers. The most popular of them are Gmail, Outlook, Yahoo! Mail. Depending on the reliability of the service, the level of its spam protection may differ. Generally, sophisticated services have multiple spam filters with different algorithm types. The well-known example is a spam trigger words filter. It doesn’t allow mail messages with forbidden phrases or symbols.
  • Anti-spam law operates in many countries. Violation of the norms leads to criminal liability and penalties. The laws apply to personal information theft, phishing activities, user’s data collection without the permission, etc. For instance, the CAN-SPAM Act protects American consumers from spam.

All those sides interested in proper behavior on the network unite to combat spammers and scammers. This cooperation leads to a safer user experience on the Internet. However, the spam filters and traps sometimes catch innocent email marketers, who just want to communicate with their audience.

Learn how to send emails to multiple recipients without them knowing.

Considering the main anti-spam techniques, we’ll try to handle how to stop emails going to spam.

How to Avoid Spam Filters

We’ve divided the reasons for getting under the spam filters and ways to bypass it into five main categories:

  1. Technicalities
  2. Subscribers base
  3. Text content
  4. Mail messages design
  5. Law regulations

Each of the list item has about six options. So, we start with 30 tips on how to get rid of the spam filters effect.

Chapter 1

Sender’s name

When a consumer receives a message, the sender’s address must be recognizable. It should indicate the brand’s name. Messages from an unknown address with a common name are more likely to go to spam. For example, you should avoid addresses with numbers or including ‘noreply’ before the domain name. The best choice is to assign a brand name to the address, specify the sender’s name.

There are penalties for the address absence or false information in the ’from’ field when using email as ad.

DNS Blacklist

The Blacklists are formed from IP addresses and domains detected in spamming. Due to bad reputation, these IPs are banned, and their messages don’t reach the subscribers mailboxes.

You can check whether your IP is blacklisted. Here is the website for testing your mail server’s address and domain – https://www.spamhaus.org/lookup/. The test includes the most reputable Blacklists used by major ESPs.

Email Service Provider

The ESP choice largely determines the success of email delivery. If ESP is recognized as reliable, protected, you have higher probability to reach subscriber’s inbox. Thus, services with a high trust level often block messages from untested, unknown or disreputable ESP. We’ve mentioned some of the free proven services above.


Another way to improve your domain name ratings is to enlist the reputable organizations support. Certification guarantees an increased delivery rate. The sender gets benefits after adding to the whitelist of prove mail addresses. These services require an extra expense.

Spam test

If you have doubts about spammyness of your message, check it in a special program. It simulates spam filters algorithms and tests email by different criteria. There is an example of a service – http://isnotspam.com. Before getting to the recipient mail server, you see online report matching your message with the basic requirements.

Chapter 2

User’s permission

Sending alerts only after a user’s permission is a strict rule specified in the anti-spam laws. Therefore, your entire subscriber base should consist of those who have given their consent to receive email from your company.

Double opt-in

To prevent random users from entering your email list, it’s better to double-check their subscription intention. This approach will reduce the number of bounces afterwards. Moreover, you’ll make sure in real amount of user’s interest to the product.


A good indicator for evaluating your email address as trustee is its presence in the recipient’s contact list. Suggest your subscribers to add your mail data to their address book. This measure almost guarantees that your messages won’t end up in a spam folder. It’s a strong signal for ISP to put your IP address to the whitelist.

Let them unsubscribe

The best way to keep the consumers is to let them choose freely. The creators of anti-spam laws adhere to the same idea. Therefore, in your email you need to provide a simple unsubscribe form. If the user wants to unsubscribe, but does not find how, he will simply ban you. So, provide them with opt-out option.

Learn how to unsubscribe from emails without unsubscribe link.

Inactive users

Constantly monitor your subscriber’s activity. If you notice that an addressee is not receiving or opening your emails for a long time (you should set your own duration), delete their contact from the database. The greater undelivered messages number for campaign, the worse this affects the domain reputation. Subsequently, this may worsen the common deliverability.

Sending frequency

The optimal frequency of sending messages depends on the business peculiarities, the audience involvement. You should analyze the campaigns stats. Pick the frequency when you don’t lose subscribers but increase clickability. If you too rarely contact with the audience, they’ll just forget you. However, your communication should be valuable and not obtrusive for the user. That’s the best way on how to avoid spam filters when sending emails.

Bounce rate

Email bounce rate is the percentage of the addresses, which returns your messages. There are hard and soft bounces. If the subscriber’s mail server returns your messages constantly, it means hard bounce. The reasons of delivery failure depends on address correctness, or technical problems. If you can’t solve the problems it would be better to exclude this address from your database. The soft bounce mostly becomes hard after five failed delivery attempts. You can check all possibilities to restore connection with the receiver’s server. But, if the bounce rate is high, it’s a signal for ISPs to lower your sending reputation. Thereafter, your chances of getting into spam folders will increase.


The customer should know your product. Loyal audience is interested in communication, therefore the engagement indicators are higher in that case, and your domain trust level as well. Re-engagement lengthens the interaction with the user, and leads to the sales funnel final stage. Find out your audience interests, create the new topics for emails and aim for personal dialogue.

Chapter 3

Subject line

The subject line and the sender’s name are the first points the recipient reacts to. The spam filters act in a similar way. Their algorithms determine not only separate words, but the general context, the construction of phrases as well. For example, discount offers are often go to spam. The filters catch messages similar to guaranteed spam from their bases.

Some general guidelines for subject line writing:

• Be careful with the numbers in the title;

• Avoid CAPS LOCK text;

• Don’t use many exclamation marks;

• Focus on the successful examples;

• Try to speak a common language with your customers.

Among the successful examples of non-spammy messages, the interrogative subject lines are mentioned.

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Spam trigger words

Still it’s better to avoid spam trigger words. ‘Best price’, ‘Free’, ‘Lowest price’, ‘Win’, ‘Money’, ‘Million’ and so on. Spammers use it too often, you shouldn’t do the same.

The title matches the content

Be honest with your customer. The subject line should briefly describe the message body. If you use the heading only for attention attracting without matching the context, your message will be marked as spam.

Text clearness, grammar and spelling

Text checking before sending saves from unforgivable mistakes. Make sure about the message clearness for the user. Anti-spam algorithms detect unreadable texts. Grammar and spelling are extremely important too. You can check text correctness in special services.


Spammers use large amount of links to force recipient to clicking on one at least. Don’t follow their lead. It’s better to use the main Call-To-Action button to redirect the subscriber to your landing page. This behavior is more suitable to avoid filters.

Chapter 4


Big images slow email load time and decrease deliverability. Moreover, it can display incorrectly in the subscriber’s email client. The best illustrations complement the text content. If you use an image, cut unnecessary details, resize it without loss of appearance quality and check the final view before sending.

Media content

Video and audio content is better placed on external web resources. Just post link to a page with a clip in the message if you want subscribers to watch it. This will prevent the video from improper displaying on the recipient’s side.

HTML, JavaScript

Avoid using dynamic scripts in email. JavaScript and Flash elements alert spam filters. These components are at risk for ISP.

Some mail clients automatically block HTML to protect receivers from security vulnerabilities. So, you should use both the plain text and HTML to reach more users with your message. HTML version contains brand design, and some recipients will get it.

Attached files

To prevent emails going to spam forget about the attachments in email. The filters react badly to it. If you want to provide your customers with a presentation or a price list, redirect them to the website page with this information.

Embedding forms

The forms are insecure components for emails. As in the case of attachments, add a link to the form to fill on the website.


Too bright elements, underscores, bold print look sloppy in email. Maintain a professional style in dealing with customers, and in the messages design. Simplify your texts, select corporate font and color. This will cause more subscriber’s trust.

Chapter 5

Email lists by third party

Never buy the email lists by third party. This is contrary to both anti-spam law and business ethics. Furthermore, these lists often include non-unique inactive addresses detecting by spam filters. Thus, getting into the Blacklist entails long-term reputation restoring of your domain address.

Abandoned addresses

There are services for checking email addresses. This one for example – http://mailtester.com. It verifies if the address exists, or if there any problems with connection. Spam filters are very sensitive to a large number of inactive addresses in the sender’s database. So, if you have doubts about some of them, or your open rate is low, pay attention to this option.

Opt-out option

A simple option for unsubscribing from emails is a strict anti-spam rule. You should provide recipient with clear explanation on how to opt-out of getting your emails. Every your message must include link or button to stop receiving emails from your company.

Misleading header information

The deceptive data in the ‘From’ field or the misleading sender’s name provoke the fines receipt under anti-spam laws. Show your good intentions and check information before sending emails.

Reliable company data

Providing the recipient with correct physical postal address and official company name are law requirements too. It’s an important point of regulation, if you send emails as an advertisement.


In order not to be blocked by subscribers, comply with email etiquette.

We have compiled some rules for ethical user interaction:

  • Indicate in the subject line the user’s problem you solve instead of the product you offer.
  • The personal appeal is more acceptable. Marketing strategies are based on the individual customer interaction now.
  • We’ve mentioned above the importance of user’s consent for receiving your emails, double opt-in, and opt-out possibility.
  • The mail messages should have value for the audience. Choose the relevant topics to send emails. Use subscriber’s segmentation to deliver the information customers really need.
  • Proofread every message. Try to re-read your emails several times, check it for correctness, clearness, nice appearance.  
  • Be open and honest with your consumer. You build trust gradually, and it gives high results afterwards.


Even compliance with all the above recommendations does not guarantee that your email will avoid getting into spam. Nevertheless, largely it will reduce the chances of being ignored by your subscribers.

Let’s sum up as a list of the dos and don’ts:

  1. The sender’s name must identify the person or your business
  2. Check if there is your address in the major Blacklists
  3. Pick a reputable proven Email Service Provider.
  4. Try to get certified by a reliable organization.
  5. Go through a spam test before sending messages.
  6. Get the user’s permission for email delivering
  7. Ask them twice about the intention to subscribe
  8. Ask subscribers to whitelist your address
  9. Provide them with simple unsubscribe form
  10. Exclude inactive users from email list
  11. Email with the optimal frequency
  12. Remove hard bounces from the list, and watch out for soft ones
  13. Re-engage your audience with valuable content, use targeting
  14. Make non-spammy subject lines
  15. Avoid the spam trigger words and phrases
  16. Let the subject line match the message body
  17. Keep track of message spelling and grammar
  18. Remove extra links from email, leave the main only
  19. Discard unnecessary images or cut them back
  20. Redirect to media content by the  link from email
  21. Don’t use dynamic scripts
  22. Avoid attachments
  23. Don’t use embedding forms
  24. Use a limited fonts and colors number for the message
  25. Avoid buying email lists
  26. Check if the user’s address exists before sending email
  27. Provide the recipient with full information about opt-out
  28. Don’t use misleading data in the ‘From’ field
  29. Write down the actual company address and name in the messages
  30. Be ethical in correspondence

Now you know how to keep away from the spam filters. The tips above will help you in achieving better email marketing results. Your subscribers are waiting for messages from you, do your best.

If you have any questions about email campaign launching, ask our support team.