Tips and Tricks to Avoid Spam Filters

As a marketer, it is important to reach out to potential customers through all mediums. Of all the mediums, email tends to be an effective and cost friendly way to promote your product or services. You can do a lot with email marketing. And since so many businesses are taking up this regime, many such emails end up in the trash folder of recipients thanks to spam filters. These filters have algorithms to detect a promotional email and qualify it as spam. Even if your email is permission based, these filters may stop them from reaching your client.

  • Only 79%. According to an analysis by Return Path, only 79% of such emails make it safely into the inbox.

Hence, it is important to understand these filters and learn how you can avoid them.

How do Spam Filters Detect Spam?

Many major ISPs like Yahoo or Google have built in spam filters and these filters have a designated set of criteria. The list of these criteria is very long and each criteria is weighed and in the end based on these weights, your email is assigned a spam score. Your email goes to spam if this number exceeds a certain set limit.

Some criteria include:

  • The reputation of your IP address or domain.
  • Subscriber’s relation.
  • Safety of links contained in the email.
  • Image to text ratio.
  • The subject text.
  • Text version of the email.

These filters are getting smarter each day. They learn from a user’s behavior. Let’s examine a scenario.

Tom’s Story

Tom is a student who surfs a lot online and gets many promotional emails. He always sends emails from salons and spas to his trash folder. One day he bought a spa day voucher for his girlfriend and he willingly gave his email address to hear about promotions. When they sent him an email about a great spa deal, it directly went into Tom’s trash folder. Why? The filters have detected that he was not interested in emails from beauty salons.

They track the actions of the users in order to learn about them.

  • The time a user takes to read an email.
  • If the user likes images (Images Enabled).
  • The time user takes to scroll down an email.
  • If the user opens a certain email or not.
  • If the user forwards the email to someone.
  • The folders created by the user (Travel, Restaurants, Fashion, etc.).
  • If the user marks an email as spam.

Email Marketing

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Ways to Avoid Spam Filters

Now that you know what these filters are capable of, its time you learn how to tackle them. There are ways to make it pass these filters and reach the inbox of the intended recipient. However, the most important thing is permission. There is a greater chance your email goes into spam if you are sending it without the recipient’s permission. If you have the permission, here is how you reach the inbox:

High-Quality Content

This is the best way to reach the people who want to hear from you. You can increase subscriber engagement with the help of your content.

  • You need to avoid all capitals, exclamation marks, and vivid colors and make your email more professional. Your subject needs to be engaging.
  • Avoid sales words and triggers and use wise words in your email. There should not be a lot of links let alone risky links.
  • Many spammers use images to display content as filters cannot rad text from images. Sending a large sized image will qualify your email as spam. According to, the text to image ratio should be 60/40.

Check out this video about tips to creating an engaging subject line.

Using Double Opt-In

You can use the double opt-in option with your email subscription form. It is a recommended way to gain the permission of subscribers and their information. It works like this:

  1. User fills the sign-up form on the website
  2. User receives an email with a confirmation link
  3. User clicks confirmation link to confirm subscription

This tool ensures that your subscribers are real people who are actually interested in your products or services. You receive a timestamp, the IP address, browser information of the user. This serves as a proof of permission.

  • The unsubscribe rates are 7% lower for double opt-in as compared to single-opt-in.

Avoid Purchased and Rented Lists from Risky Sources

Even when email lists can do wonder for the business in bringing new business, but if bought from the fishy seller, these lists can increase your bounce rate and in worst case scenario make you end up on a blacklist. They will not really help you with your promotion as half the people would not even be interested in your service. You should make your contact list ethically and add people who may have an interest, too. And avoid scrapping emails off the internet, it will be futile and may even have legal repercussions. Here is how you can grow your list.

Act Now

According to, email marketing lists degrade by 22.5% annually. Engage with subscribers right from the beginning, perhaps send out a welcome message. Your contacts can change over time so the best practice is to keep your lists updated because stale addresses can increase bounce rates and effect your reputation.

Clear Option to Unsubscribe

This is also required by law that you add an unsubscribe line in your promotional email. Many people tend to hide it under the text or keep the font illegibly small. This should be avoided and the unsubscribing link should be prominent. People who are no longer interested in your email will opt out giving you an updated list with only interested customers.

Personalize and Consistent Content

Make the content personalized as subscribers like this. Address a subscriber by their name. Emails with personalized subjects increase the chances of opening by 29%. And consider your emails an extension of your website or brochure. It should conform to the image people have about your services. Avoid going away from your general theme.


The basic key is to keep things genuine and engaging. Your promotional emails can pass the spam filters if it has quality content, interested audience and a reputable email service. According to McKinsey, email is 40 times more likely to be effective at acquiring new clients than powerful social medias like Facebook or Twitter. This speaks volumes about how email marketing can play a big role in your success.