Apache SpamAssassin is a filtering program that uses a variety of spam-detection techniques and provides a spam score to every email: 5 being considered as spam.
SpamAssassin is used by most ISPs (Internet Service Providers) and individual domains as a spam-filter. Meaning that a bad grade (4 or above) will impact severely your deliverability.
SpamAssassin developers keep the factors involved in the score calculation public.
These are some key elements checked by SpamAssassin:
However, SpamAssassin is a complex and dynamic program, including scores from other spam filters in its own score calculation.
Spam filters are using keyword detection to spot junk emails and make sure your inbox stays clean. This is why you should choose carefully the words used in the subject and body of your emails. Here's is the ultimate list of spam-trigger keyword that you should ban from your email content in 2021!