Hector Santos wrote:
Just to make sure I am following the question, are you referred to the
angle bracketed domain literal?
Oops, meant square bracketed domain literals.
If so, insights predating 1995-2000 DRUMS years with the 1982 RFC821 and
the 1989 "Holy Bible" RFC1123 and the already existing Received: header
format would help with the prior art. RFC1123 cleared it up:
5.2.8 DATA Command: RFC-821 Section 4.1.1
Every receiver-SMTP (not just one that "accepts a message for
relaying or for final delivery" [SMTP:1]) MUST insert a
"Received:" line at the beginning of a message. In this line,
called a "time stamp line" in RFC-821:
* The FROM field SHOULD contain both (1) the name of the
source host as presented in the HELO command and (2) a
domain literal containing the IP address of the source,
determined from the TCP connection.
* The ID field MAY contain an "@" as suggested in RFC-822,
but this is not required.
* The FOR field MAY contain a list of <path> entries when
multiple RCPT commands have been given.
Is this what you are referring to?
Sometimes a host is not known to the translation function and
communication is blocked. To bypass this barrier two numeric
forms are also allowed for host "names". One form is a decimal
integer prefixed by a pound sign, "#", which indicates the
number is the address of the host. Another form is four small
decimal integers separated by dots and enclosed by brackets,
e.g., "[126.96.36.199]", which indicates a 32-bit ARPA Internet
Address in four 8-bit fields.
I will note murray, I don't seem to recall any special thinking other
than taking what HELO field value and doing a macro replacing for the
Received: from HELO.HOST by LOCAL.HOST; TIME-STAMP
But I also do recall looking at RFC822 messages to see what other
receivers were doing for the Received: trace line, not just for this
but for other informations to add.