Exim (and some other MTA's) can actually be configured to follow
EITHER behaviour.
Some MTA sites will validate recipient addresses at the time of the SMTP
session, and issue 5xx codes in response to RCPT TO (or sometimes after
the completion of the DATA section) (and then the responsibility for
generating a nondelivery notice falls to the system trying to send the
message).
Some MTA sites will accept any recpient address, accept the SMTP
message, and then validate the recipients afterwards, and if it finds
a nonexistant/invalid recipient, the responsibility for generating a
nondelivery report falls to the server that accepted the message.
Basically, *if* a receiver-SMTP says "2xx" to a sender-SMTP issuing MAIL
FROM, RCPT TO, and the completion of DATA, then IT is responsible for
any bounce messages.
But, *If* a receiver-SMTP says "5xx" to the sender-SMTP, at any point,
then it is the sender-SMTP's responsibility for generating bounce
messages.
On Thu, 16 Aug 2001, Dan Egli wrote:
> Well EXCUSE ME! This happens to be an EXIM list anyway, and as pointed out
> in a previous message, EXIM follows that same behavior!
>
> ----- Original Message -----
> From: "Phil Pennock" <Phil.Pennock@???>
> To: "Exim Users" <exim-users@???>
> Sent: Thursday, August 16, 2001 2:40 PM
> Subject: Re: [Exim] errors_copy
>
>
> I'm sorry; I keep forgetting the international audience. I tend to
> assume that people can read English and understand the meaning of words
> like "if".
> --
> "Both oligarch and tyrant mistrust the people,
> and therefore deprive them of arms."
> --Aristotle
>
>
>
> --
> ## List details at http://www.exim.org/mailman/listinfo/exim-users Exim details at http://www.exim.org/ ##
>
--
