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Re: [LUG] Sendmail - Clone all incoming email to compare spam filters?

 

On Thu, Mar 25, 2010 at 8:12 PM, Sam Grabham wrote:
> Does anyone know how to clone all incoming email traffic to 2 separate smtp
> servers.
>
> I want to prove a concept but need the same emails on both servers to
> compare.

Not sure how much you're restricted to sendmail, but qpsmtpd -- an
highly configurable, open source MTA, written in Perl -- is really
good at that kind of thing.

As Gordon said, be aware of backscatter. If one of the two SMTP
servers has a (temporary) problem and can't deal with a certain email,
you probably don't want it to send a DSN to the sender.

In this context, it's also worth thinking of XCLIENT, which is a
little known Postfix extension (but it's easy to write a plugin for
qpsmtpd that does the same) that lets you tell the recipient MTA about
the original sender's IP address and HELO/EHLO domain. Useful for
DNSBL lookups, even if all mail comes from the same MTA.

Martijn.

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