🚀 go-pugleaf

In article <208@frcs.UUCP> paul@frcs.UUCP (Paul Nash) writes:
>The effect on the headers is roughly as follows (`gatebox' is the
>[ficticious] `sendmail' pervert):
>
>	incoming			outgoing
>	
>	To: user@toaster		To: toaster!user@gatebox
>	From: me@tinytoy		From: tinytoy!me@gatebox
>
>The administrator of this particular machine feels that this is
>perfectly reasonable, and even desirable, so that mail gets routed
>the way that they think fit.  However, others of us think that this
>is not terribly sociable, and want our addresses left alone.
>
>I have tried digging through RFC822, but it has cast no light on
>the subject.  My gut feel, though, is that each mailer should only
>rewrite the `Path:' field (and add a fifteen-line `Received:' field).
>The rest should surely be left alone (after all, _I_ know who I am).
>Are there any Mail Gurus out there who can elighten us?

The rule is that when a gateway forwards mail into the Internet, the
"@<host>" portion of the addresses in the header must all be recognizable
to Internet hosts.  Prior to the domain system, this meant that the <host>
had to be in the Internet host table.  Now it means that the <host> must
have either an A or MX record in the domain database.  So, if "toaster" and
"tinytoy" are in the domain database there should be little need to rewrite
them.

That's the ideal.  However, the fact is that many systems are still running
old mailers that don't know how to use MX routing.  So, if they want most
hosts to be able to reply to the mail, it's safer to put an actual Internet
host in the "@<host>" portion of the addresses.

You may know that tinytoy recognizes the host name toaster and knows how to
route mail to it.  But this may not be true for all users on your side of
gatebox.  And do you really know what protocols are supported by all hosts
you will ever send mail to?
--
Barry Margolin, Thinking Machines Corp.

barmar@think.com
{uunet,harvard}!think!barmar