Understanding the spam score of an email: points, rules and threshold
Many receiving servers rate every email with a score. Once you understand the score, you can see what pushes a mail into spam and act on it.
What a score means
Many filters add up points for one message. A common example is SpamAssassin. Each rule that matches adds points. The higher the total, the more likely the mail ends up in spam.
The individual rules
Each rule has its own code, for example for certain words in the subject, an unfavourable ratio of images to text, a missing plain-text part, or broken links. The header shows which rules matched. The code names the problem; the fix is in why emails go to spam.
The threshold
With SpamAssassin, the usual threshold is 5 points. Other providers set their own limits. There is no fixed rule that applies everywhere, so treat the score as a hint, not a verdict.
What you do
- Read the rule codes in the header of a test mail, for example with our header analyzer.
- Fix technical findings first, such as missing authentication, because they often add many points.
- Then check content and sending: plain-text part, image-to-text ratio, links and the unsubscribe option.
- Test again until the score is clearly below the threshold.