I normally would not cross post this but it does relate to internet mail as
a whole and therefore applies to Exchange 5.5 and 2000.
I had the unfortunate situation recently where a configuration error opened
us up to relaying. Once notified that this was the case, I quickly put a
stop to it. I then spent the next several hour/days having our address
re-tested by the various "blackhole" lists. Most quickly had my systems
re-tested and declared that I was not longer a relay. I did run into one
that has so far refused to remove me from the list. When I contacted the
person responsible for blocking us ([EMAIL PROTECTED]) I got this
response:
>Relay test 1
>>> RSET
<<< 250 Rset state
>>> MAIL FROM:<[EMAIL PROTECTED]>
<<< 250 <[EMAIL PROTECTED]>... Sender ok
>>> RCPT TO:<[EMAIL PROTECTED]>
<<< 250 <[EMAIL PROTECTED] Recipient ok
>Relay test result: host appeared to accept a message for relay.
>Please don't waste my time with lies. You will not be removed until you
>pass ALL tests.
>--
>Dr Paul Cummins - Internet Engineer | /"\ ASCII RIBBON
>Tel: 07021 117179 Fax: 07092 105150 + \ / CAMPAIGN
>Email: [EMAIL PROTECTED] | X AGAINST HTML MAIL
| / \ AND POSTINGS
I then explained that the mail system would not reject mail until the data
command was sent and got this response:
>No, you have failed the relay test ORB UK applies. If you want to be out
>of our list, you comply to our testing processes. You are an open relay,
>Close it, or you stay listed. Rejecting on 'DATA' is not compliant with
>RFC2822.
Good Evening
Now, of course, RFC 2822 says nothing about DATA verb or when to check for
validity that I see. I feel that RFC2821 would be of interest when it comes
to how to handle a message if you're a SMTP host:
I won't post the full RFC but just highlight the relevant parts:
Section 3.7 - If it declines to relay mail to a particular address for
policy reasons, a 550 response SHOULD be returned. However, the message
policy can't be checked until the entire message has been accepted since the
mail host is not allowed, for any reason, to end the conversation with the
exception of timeout.
Section 4.1.1.3 RECIPIENT (RCPT)
Of course, since hosts are not required to relay mail at all, xyz.com MAY
also reject the message entirely when the RCPT command is received, using a
550 code (since this is a "policy reason").
6.1 Reliable Delivery and Replies by Email
When the receiver-SMTP accepts a piece of mail (by sending a "250
OK" message in response to DATA), it is accepting responsibility for
delivering or relaying the message. It must take this responsibility
seriously. It MUST NOT lose the message for frivolous reasons, such as
because the host later crashes or because of a predictable resource
shortage.
Sorry for the extra long post, but Dr. Cummins has refused to continue the
discussion with me and has block my mail address. I would like your opinion
on this matter on who is correct.
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