DOC: doco for exim-spam

config/filter.d/exim-spam.conf

@@ -1,5 +1,17 @@
 # Fail2Ban filter for exim the spam rejection messages
 #
+# Honeypot traps are very useful for fighting spam. You just activate an email
+# address on your domain that you do not intend to use at all, and that normal
+# people do not risk to try for contacting you. It may be something that 
+# spammers often test. You can also hide the address on a web page to be picked
+# by spam spiders. Or simply parse your mail logs for an invalid address 
+# already being frequently targeted by spammers. Enable the address and 
+# redirect it to the blackhole. In Exim's alias file, you would add the 
+# following line (assuming the address is honeypot@yourdomain.com):
+#
+# honeypot:  :blackhole:
+#
+# The use the jail.local filter = exim-spam[honeypot=honeypot@yourdomain.com]
 
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