Ultimate Guide: How To Avoid Spam Filters For Your Email Marketing Campaign


Spam filters are a great thing. They are intended to keep the bad guys out. It’s like having a high wall around a fortress. But sometimes, the good guys get walled out too. Then things get highly frustrating. This is the story of the average email marketer and spam filters. 


It’s easy to choose to condemn the wall when it keeps an email marketer and their good marketing intentions out, but one thing is certain, it is never deliberate. After all, people are interested in whatever brings them benefits and improves their life. So, how can an email marketer with helpful content avoid spam filters in their email campaigns? How can they make sure their message will arrive in the recipient’s inbox without being arrested and sent to spam-folder prison? This is the ultimate guide on how to avoid the apparent “catch-all” effect spam filters often have on email marketing campaigns.


Table of content: 


What Is Spam Email Anyway?

To start, we need a proper definition for "spam email." Spam email is also known as mail spam or junk email. It is defined as unsolicited email sent in bulk—that is, messages sent to individuals that know nothing about the sender or have previously refused email from the sender. Therein lies the problem with spam—it is unsolicited.

Spam has gained popularity since the early 1990s, and it now affects every single email user. From African princes offering to share their lavish inheritance with you, to counterfeit messages that appear to come from a reliable source asking for personal information. There are also simple emails arriving from senders you do not know and unsolicited commercial emails sent in bulk to a purchased (sometimes stolen) mailing list that contained your email address.

These types of email are what spam filters scan and decide should be in the junk folder (spam folder). Sadly, genuine emails from marketers can contain all the elements of spam email, such as spam trigger words. Read on to learn at least 20 ways to avoid having your messages confused with spam.

Spam emails have created so much trouble that, according to ReturnPath’s research, a full 21% of emails sent by genuine marketers actually end up in subscribers’ junk folders. This is the email marketer’s frustration; that one small error can easily get your messages classified as spam. Worse still, you can be blacklisted and face near irreparable damage to your email deliverability and reputation.


How Email Messages Get Classified as Spam


To understand how to beat spam filters as an email marketer, you need to understand first the process that qualifies your email message to be sent to the spam folder. This will help you craft better-targeted emails that your subscribers will see every single time.

ISPs, Email Content, and Deliverability

ISPs (Internet Service providers) always review mail servers when deciding to accept or reject a message and there are standards for excellent deliverability. The content of messages is more important than many email marketers realize and ISPs run messages through content filters to determine if they are junked or inboxed.


Spam Email Vs Phishing Email


Spam email is often confused with phishing email. Spam however, does not always have criminal intent whereas phishing does. Both email types use similar approaches to content, since phishing email leverages spam email techniques to cast their net as far as possible.

But often phishing emails are designed well enough to get past spam filters.


What Is Spam Email Filtering?


Spam email filtering is the process of using software to catch and quarantine unsafe emails. There are multiple security mechanisms such filters use to identify spam messages, like comparing the source of the email with the published blacklists of mail servers known to relay spam or checking the number of recipients of the email.



How Spam Filtering Works


Email filtering solutions use a set of protocols (rules) to determine what gets to the inbox and what gets weeded out. Filters organize email according to certain rules or criteria. They were designed initially to identify spam or send it to the spam folder. Some ESPs use email filters to categorize messages for inbox organizations.

Types of filters include:

  • gateway spam filters
  • third-party (hosted) spam filters
  • desktop spam filters


How To Report Spam Email


Because of how potentially dangerous spam is, there are several avenues to report spam email. Reporting spam email is not the wasted effort that some might think it is. Apart from trusting your ISP and your spam filters, this is one more thing you can do to combat spam. Forward unwanted emails stating that you are complaining about being spammed to 1) your email provider, 2) the sender’s email provider and 3) the FTC.


How To Stop Spam Email


To stop spam from taking over your email, you can take a few steps right away:

  1. Never respond to spam.
  2. Change your email address.
  3. Hide your email address.
  4. Invest in a third-party spam filter.
  5. Train your filter.


How To Get Through Spam Filters


There is an art to getting past spam filters. But, it can be learned. To ensure your emails reach the destination inboxes and improve your open rate:

  1. Choose a reliable email service provider (ESP). Any good reputation they have depends on the good reputation of their clients. ESP clients delivering high-value content with high scores on their IP addresses improve the ESP’s trustworthiness.

  2. Use a recognizable sender name. Send emails from email addresses containing personal names and or brand names. This is because people prefer to open emails with personal names in the from box.

Convince and Convert says 43% of email recipients will click spam simply because of what information they see in the “from” field, name and address.

Top ESPs also watch the from” field with keen interest. Using a blacklisted IP address and obscure “from” field name like 202019@yourdomain.com or noreply@yourdomain.com could cost you in terms of deliverability.

  1. Obtain third-party certification. You can tell spam filters you are not a spammer if you get sender accreditation from a third party.

These companies assess your email practices and certify that you’re a trusted sender. This ensures more inboxes tell ISP spam filters to let your emails get through.

  1. Check your IP address reputation. Your IP address reputation directly impacts your email deliverability. Tools like Multirbl. Vali and MxToolbox let you check if you are a blacklisted sender.

  2. Test your emails before sending them. Testing improves your chances of reaching subscribers’ inboxes. There are many high-quality spam content checkers. Mail Tester tests your email quality by mimicking spam filters and assigning a score based on the spam trigger words it finds within the email.

  3. Always be learning. Keep updating your knowledge of spam filtering technology, anti-spam law and ISP practices. The laws are constantly evolving regarding technology as a whole. Internet marketers must know the basics of the CAN Spam Act that defines the fundamental rules for commercial email. It states requirements for commercial messages and empowers the recipient to stop you from emailing them. There are strict penalties for violation, and it does not apply to bulk email alone.

    Consistent learning will improve the outcomes of your triggered marketing campaigns over time.

  1. Keep email lists clean. To avoid spam traps and filters, ensure you stick to certain standards, including never buying email lists.

  2. Remove hard bounces from email lists. Sender reputation is a function of bounce rates. Carefully manage your reputation to improve deliverability. Emails to inactive addresses over time are recorded by an ISP as a spam trap hit. Once you are notified of a bounce by your ISP, delete that email address.

  3. Respect your unsubscribers by ensuring they have the option to unsubscribe when they want to. A simple one-step process makes it as painless as possible.

  4. Use subject lines wisely. 69% of people mark an email as spam when the subject line SCREAMS AT THEM (when you type it all in uppercase). Most people prefer an all lowercase headline and use of only a single exclamation mark.

Other ways to keep your email spam score healthy include:

  • Being careful not to make false promises.
  • Avoiding rich media content like video and Flash movies.
  • Not embedding any forms, which are often a huge security risk.
  • Not including attachments.
  • Using as few colors and fonts as possible.
  • Using as few images as possible.
  • Ensuring images display correctly.
  • Offering plain text and HTML versions of email.
  • Using correct spelling and grammar.
  • Sending content that fosters communication.
  • Above all, paying attention to technicalities


Spam Trigger Words


These are words that set off the alarm bells in a spam filter. Avoid these words in your emails at all costs.

The list includes words like promise, quote, offer, order now, open, and problem. 


Spam Traps


Major ISPs also use a type of fraud management tool called spam traps. They blacklist providers to identify spammers and block emails from them. A spam trap is an email address, only it is not for a real person and cannot be used for communication. Not cleaning your email lists regularly can set you up for the harsh effects of spam traps.




Spam email will continue to be a tool of choice for criminals as long as people increasingly communicate via email, and this makes things more difficult for marketers. However, you can enjoy increasing success in your campaigns by applying the tips in this ultimate guide to make sure your messages won't be mistaken for spam.