Re: Need help solving a Sender/From address dilemma

Hi,

Thanks for all the replies.

Here's my solution for Exim.  It seems to work quite well.

The basic principle is that TMDA works with From, Exim works with sender, and 
now with the following changes, Exim checks From as well - protecting TMDA 
from this type of spam.

Changes to exim.conf:

# RJR 27/4/10: do a soft host verify so we can check for failure
# in an ACL
helo_try_verify_hosts = *

# To protect TMDA from some spam, we check the From lines
# RJR 28/04/10
acl_smtp_data = acl_check_from

acl_check_from:

      #
      # Block invalid hosts for some domains
      # Some spam claims to be from, say, [email protected] but is not sent
      # from an amazon server.
      # The spam's From line is different to the sender address.  We need
      # to check the From line because that's what TMDA uses.
      # RJR 28/04/10
      #
  deny  condition = ${lookup{${domain:${address:
$header_From:}}}wildlsearch{/etc/exim/verify-hosts-domains}{yes}}
        !verify = helo
        log_message     = Spam (type 3) from $header_From:, sender 
$sender_address at $sender_fullhost

   accept

acl_check_from goes after the "begin acl" directive.

The others go in the main section.

If you're already using acl_smpt_data, then you'll have to move the above acl 
check into your current acl.

I now manually add domains into a file called /etc/exim/verify-hosts-domains.

Here's my current file:

#
# This file is a list of sending domains for which
# helo_verify_hosts must succeed.
# RJR 27/4/10
#
*amazon.com

Note that I don't specify "*.amazon.com" because that will only 
match "something.amazon.com" and not straight "amazon.com".

Hope that helps someone out there in TMDA land!

-- 
Russell Robinson ([email protected])

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