[RFCI-Discuss] Returning 250 with User Unknown

[mouss]

Jamie L. Penman-Smithson wrote:
> I've encountered a few mail servers (all running Merak) which are 
> returning 250 for recipients even when they don't exist - without 
> returning any bounce message:
>
> 220 get.z-get.com ESMTP Merak 7.4.5; Mon, 17 Apr 2006 11:49:19 -0400
> HELO rivendell.silverdream.org
> 250 get.z-get.com Hello rivendell.silverdream.org [62.3.223.135], 
> pleased to meet you.
> MAIL FROM:<>
> 250 2.1.0 <>... Sender ok
> RCPT TO:<postmaster at z-get.com>
> 250 2.1.5 <postmaster at z-get.com>... User unknown
>
> RFC 2821 states that if the recipient is accepted, 250 should be 
> returned:
>    "If accepted, the SMTP server returns a 250 OK reply and stores the
>    forward-path.  If the recipient is known not to be a deliverable 
> address,
>    the SMTP server returns a 550 reply, typically with a string such as
>    "no such user - " and the mailbox name (other circumstances
>    and reply codes are possible)."
> [..]
>    "If an SMTP server has accepted the task of relaying the mail and
>    later finds that the destination is incorrect or that the mail cannot
>    be delivered for some other reason, then it MUST construct an
>    "undeliverable mail" notification message and send it to the
>    originator of the undeliverable mail"
>
> There is no bounce, so it would seem that they are accepting anything 
> and everything and not sending any bounces. AFAICS this is in 
> violation of the RFCs, since they are required to notify the sender if 
> they are unable to deliver the message to the intended recipient.
>
> Am I right? Or not..
while the response text is bogus ("user unknown in 250), nothing proves 
they discard the message. if they deliver the message to a mailbox, be 
that a catchall address that nobody reads, then it's their problem. this 
is because they can really deliver the message to a mailbox that is read.