NOTE: it turned out that this can get dangerous; for example,
if you mark a mail coming from gmail.com spam, you'll
reject gmail.com, which is obviously not a bright idea. I'll leave the
article here, but be warned.
Recently I noticed that I get many spams from the same sender domains. In this case, I could safely apply a manually updated list to postfix to reject these domains in the first place.
Go to the spam Maildir's cur folder:
#!/bin/bash
cd /path/to/spam/Maildir/cur
touch /etc/postfix/sender_checks
grep -ri ^From * | awk '{ print $3}' | grep @ | sed 's/[<>]//g' | cut -d"@" -f2 | sort | uniq >/tmp/spammer
sed -i "s/^/\//g" /tmp/spammer
sed -i "s/$/\$\/ REJECT\ Byez\ spammer/g" /tmp/spammer
cat /etc/postfix/sender_checks >> /tmp/spammer
cat /tmp/spammer | sort | uniq > /etc/postfix/sender_checksAdd to /etc/postfix/main.cf:
smtpd_sender_restrictions = reject_unknown_sender_domain,
check_sender_mx_access pcre:/etc/postfix/sender_checks,
check_sender_access pcre:/etc/postfix/sender_checks,
check_sender_ns_access pcre:/etc/postfix/sender_checks,It will not catch too many spams only a few per day, but even that can be useful.
(Oh, by the way: this entry was written by Peter Molnar, and originally posted on petermolnar dot net.)
