[spambayes-dev] Re: Generating SB tokens based upon information
on the net
T. Alexander Popiel
popiel at wolfskeep.com
Wed Aug 4 18:30:34 CEST 2004
In message: <email@example.com>
Brad Knowles <brad.knowles at skynet.be> writes:
> In the case of reverse DNS, all that work will already have been
>done by the system before you ever get the message. All MTAs I know
>of automatically do reverse DNS lookups the moment a client connects,
>regardless of whether or not they actually attempt to use that
>information to control access. If nothing else, they need this
>information to put into the "Received:" headers that they're going to
>add to the message as it passes through.
Actually, the Received header info can come from the HELO or EHLO command
that opened the conversation, not DNS. I haven't looked to see if any MTAs
actually do it that way, but it's the way I would do it if I were writing
one... (And sure, that means a rogue could lie about identification in
the HELO... but that's why both the name and the IP appear in the
>Or, you could just parse the content of the appropriate headers that
>we just added.
I believe that's the point of the mine_received_headers option.
> We've got that no matter what. If DNS goes down, we're toast,
>period. The kinds of things I had configured is no additional
>exposure with respect to that issue.
> Indeed, all MTAs I know of are toast if DNS ever goes down, at
>least in their default configurations.
Outbound, certainly... but not for inbound.
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