Open Relay Checker before Opening MTA

Michael Still mikal at
Sun Feb 10 10:35:36 EST 2002

On Sun, 10 Feb 2002, Ben Elliston wrote:

> I realise that Neil's idea would prevent his system from *accepting*
> mail from open relays.  Another approach I have heard about is to only
> accept mail for a domain (say, from's listed MX
> hosts.  I don't know which MTAs implement this, though--anyone?

Greg Lehey's mail server does something similar to this. It also looks up
the reported IP address in DNS and checks that it resolves the the
hostname that the machine claimed. I am not sure what MTA he is using to
do all of this though.

Couldn't you do a lot of this by accepting the mail, and then filtering it
in a procmail script?



Michael Still (mikal at     UMT+11hrs

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