Subject: [Emailcore] Ticket #7: Trace header field related text in rfc5321bis

From: Alexey Melnikov <[email-masked]>
Date: Fri, 23 Jul 2021 15:29:49 +0100

Hi all,

I scanned the draft and hopefully captured all cases where trace header 
fields/Received are mentioned. Below is a strawman of what might be a 
good idea to update:

Add a new section that introduces Trace header fields. Possibly change 
4.4 to be that section and move definition of the Received header field 
into a subsection of 4.4 (e.g. 4.4.1). I found the following text in RFC 
822, which seems like a good definition:

      Trace information is used to provide an audit trail of  mes-
      sage  handling.   In  addition,  it indicates a route back to the
      sender of the message.

2.3.10.  Originator, Delivery, Relay, and Gateway Systems

    A "relay" SMTP
    system (usually referred to just as a "relay") receives mail from an
    SMTP client and transmits it, without modification to the message
    data other than adding trace information, to another SMTP server for
    further relaying or for delivery.

Add a reference to the new 4.4. after "trace information".

3.6.3.  Message Submission Servers as Relays

    As discussed in Section 6.4, a relay SMTP has no need to inspect or
    act upon the header section or body of the message data and MUST NOT
    do so except to add its own "Received:" header field (Section 4.4)

Add "and possibly other trace header fields" at the end of the above line.

    and, optionally, to attempt to detect looping in the mail system (see
    Section 6.3).  Of course, this prohibition also applies to any
    modifications of these header fields or text (see also Section 7.9).

7.6.  Information Disclosure in Trace Fields

    In some circumstances, such as when mail originates from within a LAN
    whose hosts are not directly on the public Internet, trace
    ("Received") header fields produced in conformance with this

Change '("Received")' to '(e.g. "Received")'

    specification may disclose host names and similar information that
    would not normally be available.

Thoughts?

Best Regards,

Alexey