Hello, I am currently providing an email service to a hotel. All SMTP traffic from the hotel is redirected to my Exim server, which authenticates it based on the hotel's IP address. This all works great, except recently we have found that spammers have found a way to access a computer within the hotel's network, and have thus been able to use my server to send emails. The only means by which I think I can restrict traffic so that it *truly* comes from within the hotel's IP address, is to make it so that the emails must have *only one* 'Received: from' header.
To further illustrate what I'm talking about, here is a sample header of a spam email sent through the hotel network (I've changed IP addresses/server names): Received: from [83.22.55.77] (helo=freha.pl) by myeximserver.com with smtp (Exim 4.69) (envelope-from <[email protected]>) id 1NZTrC-000846-N1; Mon, 25 Jan 2010 18:40:15 +0000 Received: from unknown (156.209.88.22) by mts.locks.grgtween.net with QMQP; Sat, 23 Jan 2010 20:33:05 -1100 Received: from mts.locks.grgtween.net ([Sat, 23 Jan 2010 20:21:36 -1100]) by smtp-server1.cfdenselr.com with ESMTP; Sat, 23 Jan 2010 20:21:36 -1100 Received: from m1.gns.snv.thisdomainl.com ([14.45.232.93]) by relay37.vosimerkam.net with NNFMP; Sat, 23 Jan 2010 20:04:57 -1100 If the email was truly from just within the hotel's network, it would only have the header below (i.e. only one 'Received: from' header) Received: from [83.22.55.77] (helo=freha.pl) by myeximserver.com with smtp (Exim 4.69) (envelope-from <[email protected]>) id 1NZTrC-000846-N1; Mon, 25 Jan 2010 18:40:15 +0000 Any way to do this? -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
