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Are there spam filtering technologies that examine email headers?

For example; X-PHP-Origin header can contain an IP address that is on a blacklist; are there spam filters that would catch this?

I thought spam filters only checked the connecting client?

  • do you have an example header? I don't think I've ever seen that specific header. Do you mean the PHP originating script header? There's an X-originating-IP header. Can you provide example? – TheCleaner Jan 04 '13 at 18:34

3 Answers3

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As far as I know most of them actually do.

This is actually a very basic way of filtering spam, looking at the header and compare the senders IP to black lists such as spamhaus's SBL list.

Alex
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    Spam filters check lots of things. Headers, body content, IP reputation of sender, quantity of recipients...spam filtering is made up of many layers that, stacked together, will hopefully drop spams. – Alex Jan 04 '13 at 18:42
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Well, SpamAssassin for one.

Here's a list of the checks it performs:

http://spamassassin.apache.org/tests_3_3_x.html

The list notes the "area" of the email that are tested, e.g., body, header, etc.

Glancing through the list, it's entirely possible that SpamAssassin will not catch a blacklisted IP address used in your non-standard X-PHP-Origin header, as the header tests tend to look at specific header lines, and your referenced header probably won't be one of those.

cjc
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There are blacklists out there that use the mail headers to deny email.

In sendmail, there are many different tools available that you can configure for spam control as well.

mdpc
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