Use this tool: https://www.mail-tester.com/
Well, I know this tool and I know how it should work. But you still don't understand what is problem here.
When my user on my server send mail, and it's spam scoring is between 5 and the value set in spamassassin reject option, mail is set as spam by my server and is sent to external servers with changed title and with spamassassin explanation in mail body. It should not work like that.