On Thu, Jan 04, 2007 at 12:59:05PM -0800,
What about RFC 1123 where it states:
5.2.5 HELO Command: RFC-821 Section 3.5
The sender-SMTP MUST ensure that the <domain> parameter in a
HELO command is a valid principal host domain name for the
client host. As a result, the receiver-SMTP will not have to
perform MX resolution on this name in order to validate the
The HELO receiver MAY verify that the HELO parameter really
corresponds to the IP address of the sender. However, the
receiver MUST NOT refuse to accept a message, even if the
sender's HELO command fails verification.
The "MUST NOT" is about the statement made about verifying that
the parameter (domain name) and the connecting IP address match.
So, if the parameter is example.com, and the connecting IP address
is not 22.214.171.124, this test fails but RFC1123 tells us we cannot
reject ***for this reason***.
Where does it say you cannot reject for other reasons?
4408 is new, much newer than 1123. 4408 is about another kind of test.
Why do you feel 1123 overrides what is specified in 4408 ?
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