SpamAssassin is one of the most popular email filtering systems out there, as it is open source.
It helps users by blocking, marking, and filtering out emails that they find untrustworthy and may be spam or malware.
Among the filtering techniques SpamAssassin uses to determine spam are:
- DNS blocklists such as SORBS or Barracuda.
- Text analysis for your email header and body copy.
- Bayesian filtering.
- Collaborative filtering databases, such as email firewalls.
The filter will produce a score based on the email's performance against these checks. This score determines whether your email makes it through to your recipient.
Due to the exhaustive nature of the tests, it is difficult for spammers to make it through.
Legitimate emails will make it through all of the above and successfully arrive to recipients. However, this may be more of a gamble for email marketers or salespeople.
After all, you’re emailing multiple people daily to offer them your solution. You should have done your research and been targeting the right people with the right messaging, but it is possible to still fall through the cracks or for someone to mark you as spam.
To take the correct steps if you are marked as spam, you should monitor your SpamAssassin score, given its popularity as a spam filter.