Re: smtp questions

On Thu, 4 Mar 2004, DENNIS BYRNE wrote:

> That makes sense because "the conneting IP is in the same domain" for
> this example. I forced asdcb1@uaa.alaska.edu as the from address on
> the email, and the machine I'm developing on is on the uaa network.
> Maybe I'd be rejected if had forced asdcb1@NOTuaa.alaska.edu as the
> from address.
> OK, some more questions. Although it's imopssible to tell unless we
> had access to the email servers of uaa, yahoo and design-pt.com, why do
> they behave differently? Is this behavior built in or configured so?
> does the email server have it's own internal dns client? ... yes, I
> know it varies from server to server.

Oh, sheesh, that's a loaded question. The only thing SMTP buys you is the
connection protocol itself. It makes no guarantees about what a daemon does
with a piece of mail after the connection is severed. That's pretty much up
to the daemon's authors and the users who configured it in operation.

I can say that I've heard arguments from admins (which I don't necessarily
agree with) that will accept every piece of mail you spit at it, regardless of
whether or not even the recipient's account exists. They just shuffle it off
to /dev/null and hope this confuses spammers that might be trying to verify
what addresses are legitimate or not (lists of which they would subsequently
sell). The rationale is that the more bad addresses in these collections
there are, the less real users are going to be impacted (well, impacted beyond
the incredible waste of bandwidth used in delivering all this bad mail).

So, why do they behave differently? A combination of limitations of the
specific SMTP daemon they're using and whatever techniques the admin feels
works best to reduce spam.

(In other words, I don't have a freaking clue. ;-)

        --Arthur Corliss
          Bolverk's Lair -- http://arthur.corlissfamily.org/
          Digital Mages -- http://www.digitalmages.com/
          "Live Free or Die, the Only Way to Live" -- NH State Motto
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Received on Thu Mar 4 17:42:35 2004