Re: People forging their From: addresses

[Piet Beertema <]

    > I wouldn't go into that sort of details anyway: I'd assume
    > that *anything* can go wrong with DNS, resulting in unwanted
    > bouncing of mail from existing domains if you use 5xx.
    > So either stay on the safe side and give 4xx, or take the
    > hard approach and the risk and give 5xx.
    
    4xx is better for 2 reason's. It gives legal mail a second chance
But you give spam that same second chance, and even
numerous chances, all failing, and all at the expense
of *your* resources (and of the remote system, but I
couldn't care less).

    and if someone of your customers have set your host as a 2'nd MX 
    senders to that domain won't get 5xx error mail's if you don't
    allow 2'nd MX to your hosts.
That's a valid point, iff you are an ISP and allow such
2nd MX's.
    
    And.... If you have enough cpu/bandwidth it's actually almost
    entertaining to look on the log files when you block SPAM mail.
Very true... until the entries run in the thousands...

    The sending host will have to take care of the SPAM mail and
    it's up to them to enforce a no relay policy.
Yeah, but how do you enforce that? I've heard too many
people already who talk about it, report open relays,
but don't use tools themselves that are at hand, like
MAPS RBL and ORBS. Sure enough, they're not the perfect
or ideal tools, but if you don't use them, don't think
you'll ever get all open relays off the net.


	Piet