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SpamAssassin marks my email with reason BAYES_99 , which means the email is 99% ~ 100% spam email. What is the mechanism of SpamAssassin to detect this rule (by keyword?), and how can I avoid hitting this rule?

Raptor
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  • @Eric: Usually spamassasin is used as input filter to determine whether _incoming_ emails are spam. – fyr Jul 22 '11 at 05:41

2 Answers2

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I found this because I was using SendGrid for transactional mail, and sendgrid was sending MY mail from a server that had been blackholed for sending SOMEONE ELSE'S spam. Because the IP was blackholed, my emails were marked spam. To diagnose:

You can see if your domain or IP has been blacklisted here: https://mxtoolbox.com/blacklists.aspx

The fix was to switch to a different email transport provider.

Michael Cole
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BAYES_99 is a statistical component of SpamAssasin. It is using some sort/variation of Naive Bayes which has (to keep it simple) some sort of probability saying that some word/token is likely to be spam or not to be spam.

In "math" these could be expressed like this:

P(Class_Spam | Email)
P(NotClass_Spam | Email)

Transformations lead to e.g. this equation:

enter image description here

However there a lots of different representations of bayes classifiers. With different optimizations and statistical models.

You may disable it via spamassasin configuration. This question is not well placed on stackoverflow. Superuser would be the better fit though.

fyr
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    wow, that becomes a Maths question. How to apply this formula to my mailing system ? – Raptor Jul 22 '11 at 06:04
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    This isn't a math problem. – Michael Cole Mar 06 '17 at 02:02
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    I think the OP would like to know what they can do to prevent emails they are sending to other people from hitting this rule, not the other way around. We're having the same issue on a marketing email we're doing for a client, and trying to find information on how to we can go about wording out email, such that it doesn't get classified as spam by this test, is proving pretty difficult – thephpdev Mar 20 '18 at 10:06