Monday, July 13, 2009

TDMA - Stop email spoofing

Was getting a bunch of spam emails being forged from valid accounts on my own domain.  This was obviously being whitelisted as they are trusted sender on my email account.   Heres how to block spammers from spoofing emails.


On Ubuntu 9.04, open the /etc/exim4/exim4.conf.template file as Superuser.  Find the "acl_check_rcpt:" string and add the following rule.
# ACL Section:


# Block spoofed addresses

deny condition = ${if eq {$sender_address_domain}{$domain}{yes}{no}}
hosts = !+relay_from_hosts
message = Spammers not welcome - go away.
log_message = Spam from sender $sender_address at $sender_fullhost

Save the file and run the following command: dpkg-reconfigure exim4-config

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