Two ways the router could be enhanced to reject backscatter

Notes/Domino 8 Forum

Subject:

The Open Mic call had a number of questions about handling "backscatter" -- non-delivery reports that come from other servers on the Internet when a spammer has used the real e-mail address of one of your users as the apparent message sender.

One of the most promising approaches seemed to be a free third-party plug-in from Maysoft that it claims can reject 80-90% of backscatter while still allowing through genuine NDRs. The URL is: http://www.maysoft.com/bs

The Maysoft plug-in is described as examining the received NDRs to determine whether they are reponding to messages genuinely sent out from this Domino server.

This raised a couple of questions for me:

* Does this approach still work where inbound and outbound mail pass through different servers?

* Could this functionality be built into the Domino router code?

The answer to the second has to be yes, and it seems there are two techniques that could distinguish genuine NDRs from backscatter.

One technique would be similar to ND8's capability to thread Internet mail "conversations". If the router can identify a received Internet message as being a response to an earlier message sent by a Notes user, then the same capability should be workable for NDRs. Of course this would depend on the original message still being available in the sender's mail file. And there's a potential performance impact from the receiving server having to search for the message in the apparent sender's mail file.

The other approach is (I assume) the one being used by Maysoft. This would just examine the SMTP headers and decide whether the message appears to have been generated by a real message from your domain. If the system generating the NDR has included the orginal message as a "message/rfc822" MIME part, then there is information here that can be checked for authenticity or correlated with sent messages.

Any thoughts from Lotus' developers on whether either approach might be considered as an option for the router and SMTP tasks in 8.5?

Rupert Clayton
Chicago

Feedback response number WEBB7EVL4E created by ~Anita Asafreezenoopsi on 05/22/2008