Re: [cobalt-users] Qube 3 - How to stop spam?

[Malcolm McLeary <mmcleary@xxxxxxx>]

Hi John,

on 13/11/01 8:26 PM, John Lee at johnvero@xxxxxxxxxxxxxx wrote:

> Under the "Forwarding Rules", I set up to deny everything, no matter what IP
> and Port.  But it still doesn't work.

I've been monitoring this thread and am a bit confused ... I've not done
anything special on my Qube3s and to the best of my knowledge don't have a
problem as a SPAM relay.

Sure we receive SPAM, but straight out of the box I thought the Qube3 would
not accept any email until it was configured to do so ... it was necessary
to add the domain name to accept email for and the LAN IP range to allow
local users to send mail.  On one site, I have also nominated specific
static IP addresses of remote branch offices to allow them to relay through
the head office (I don't bother with POP before Relay).

One common thing with all my installations is that none of my Qubes use
their secondary ethernet port ... they are all simply LAN hosts and sit
behind some other internet connection device which does NAT.

I'm sure it works because I routinely get messages like;

> ERROR
> 
> A message in your Outbox could not be sent.  The server did not recognize the
> recipients.
> 
> EXPLAINATION
> 
> 5.7.1 <cobalt-users@xxxxxxxxxxxxxxx> ... Relaying denied.  Please check your
> mail first.

This happens when I accidentally try to relay through a remote Qube3 instead
of the local one.

However I am using a "usually" well behaved email tool ... SPAMMERS are
probably using all sorts of tricks to spoof IP addresses, etc so as to
appear to be "allowed" to relay email through your server.

I guess the only solution is a fully configured firewall which deals with
spoofed addresses etc and doesn't let the crap through in the first place.
Have a look at;

    Linux Firewalls
    by Robert L. Ziegler
    ISBN 0-7357-0900-9

    <http://www.linux-firewall-tools.com/linux/>

Cheers,  Malcolm

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