[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:  <p06002015bd36ae09b353@[]>
             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
Received line.)

>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.

- Alex

More information about the spambayes-dev mailing list