Re: IP number question

From: Walter Roberson (roberson_at_ibd.nrc-cnrc.gc.ca)
Date: 01/28/05 

Date: 28 Jan 2005 17:19:39 GMT

In article <ctdll3$o55$1@news.mdx.ac.uk>, <david20@alpha2.mdx.ac.uk> wrote:
|In article <ctbm99$amk$1@canopus.cc.umanitoba.ca>, roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) writes:

|>That's a bit of a misconception. MTA's are not -required- to add the
|>IP address to headers of email messages, and there are literally tens
|>of thousands of them out there which do not. The Received-By: headers that
|>are commonly added are a convention, not a requirement,

|From RFC 2821 (http://www.faqs.org/rfcs/rfc2821.html

|3.8.2 Received lines in Gatewaying

| When forwarding a message into or out of the internet environment, a gateway
| MUST prepend a Received: line, but it MUST NOT alter in any way a Received:
| line that is already in the header.

|Hence any compliant internet facing MTA MUST add in received lines.

According to RFC822, the only non-optional field in the Received:
header is the date-time, so my first statement is completely true,
and my second statement is correct with respect to what is
"commonly added".

It's also not uncommon that systems throw away Received headers,
even if they are not supposed to. 

-- 
   "Mathematics? I speak it like a native." -- Spike Milligan

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