What is SpamAssassin and how can I improve my score?

SpamAssassin is a popular open-source solution that Apache created in 2001. It is a filtering program that can be easily installed and configured on a mail server. It employs various anti-spam techniques, including Bayesian and DNS filtering.

SpamAssassin is frequently utilized for email deliverability testing and integrates with many popular email services.

SpamAssassin analyzes each email and gives it a score. The lower the score, the higher the chances of an email landing in the inbox.

Any score below 5.0 indicates an email's ability to bypass spam filters. However, scores above 5.0 indicate that an email is likely to get flagged on its way to an inbox

Four tips to improve your SpamAssassin score

1. Establish a solid sending history

Email filters pay close attention to the reputation of the sender. With each email sent, you build the domain and IP address's sending history. If you send high-quality emails that recipients eagerly open and interact with, your reputation will improve.

If your emails often bounce, are marked as spam, or are just ignored, this will hurt your reputation. Developing a positive reputation boils down to delivering emails that recipients desire to receive.

2. Authenticate

Email authentication has become a requirement for all reputable email servers, and for a good reason: it's simple to set up and highly effective against phishing. For this reason, every email should be configured with SPF and DKIM data.

DMARC, the third most used authentication mechanism, has no direct influence on the score. However, it gives you increased security and greater control over your authentication; thus, we strongly recommend it.

3. Avoid spam words

SpamAssassin has been taught to react aggressively to the typical words used by spammers as well as various, misspelled variations (such as “B3st Pr!ce”).

This also goes for other seemingly normal words and phrases like “money”, “no questions asked," and many others. Be sure to review one of the numerous lists of spam words and pick alternatives.

4. Consider your text:image ratio

SpamAssassin, as well as other filters, dislikes emails containing multiple pictures. Most of the time, it is suggested that visuals make up no more than 40% of the message body.