How to Keep Your Email Newsletters from Being Marked as Spam

What is Spam?

Spam is considered as being unsolicited emails sent to a large number of people, and generally involves email advertising for a product or service. Spam affects businesses when sending emails to market their products and even when simply sending regular newsletters.

How Spam Filters Work

Spam Filters test an email to check whether it matches specific criteria and assign points depending on the significance of each criterion. If the email contains more points than a specified value, that email is considered as spam.

Spam Filters mainly check for the following:

  • Subject Line: Does it contain ‘spammy’ words like “FREE COPY HERE!” or “YOU WON!”?
  • Recipients: Does the sender know who the recipients are, or could it be that one generated or easily guessed the email addresses?
  • Content: Is the content coded properly and does it include a text version?
  • IP address: Has this IP address been reported as a spam provider before?
  • Sender: Is the sender in the recipients’ contacts?
  • Domain name: Is the used domain valid?

Avoiding Common Mistakes

It makes no sense to spend ample time designing, coding and creating an email which then ends up in the recipients’ spam folder. Here are some other tips to avoid when writing and sending an email:

1. Avoid “spammy” content:

  • Do not use the word ‘free’ many times.
  • Do not use ALL CAPS.
  • Do not use a lot of different colours and stay away from bright ones.
  • Do not use too many exclamation marks.

2. Provide an Unsubscribe link
Even though no one would like recipients to unsubscribe from receiving one’s emails, providing a clear link to let users unsubscribe is better than having a spam complaint. Through ClickDimensions, for example, it is very easy to create this link. One can also create subscription preferences, to allow the recipient to choose exactly which email communications to subscribe to or unsubscribe from (e.g. monthly newsletter vs promotional offers).

3. Use proper HTML code
Spam Filters check for bad coding and assign points based on ways the email was coded and presented. In this case, providing a plain text alternative of the email definitely helps. ClickDimensions offers an automatic text-version generator button which makes it even easier.

4. Do not hide information in an image
One can use images to make the email more eye-catching but it is not good practice to hide content in an image. Since spam filters cannot read images, they simply assume that the sender is a spammer that is trying to trick recipients. One of the useful features that ClickDimensions provides, is that it alerts the sender if the ratio of images to text is too high.

As part of the testing process prior to sending an email, ClickDimensions offers the option to generate a spam report that is similar to the below.


This report allows the sender to change content which is most likely to be flagged as spam before actually sending the email. It is recommended to let the Spam Score under 3.0 for better delivery results.

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