Fwd: Question on standards for message ID

[Russ Allbery]

Todd Olson <tco2 at cornell.edu> writes:

> inn-workers at isc.org rejected my posting so I am sending it to you direct
> while I work on figuring out what it going on.

inn-workers dropped a bunch of subscribers over the weekend for reasons
that I don't understand yet.  You may need to resubscribe.

>> We've encountered a news client (MT-Newswatcher) that constructs
>> it's message ID as follows
>> 
>>      <stuff at host.fully.qualified:port>
>> 
>> If the port is the usual 119 then the :port is not present
>> If the port is different (as in multiple servers on one box for testing)
>> then the :port is present.
>> 
>> INN 2.2.2 rejects message IDs with the :port  as badly formed message IDs
>>
>> QUESTION:   What is the standard for message ID structure?
>>            Is INN correct in rejecting message ID's with :port ?
>>            or is INN in error?

The syntax for message IDs is defined in RFC 1036, which says:

2.1.5.  Message-ID

    The "Message-ID" line gives the message a unique identifier.  The
    Message-ID may not be reused during the lifetime of any previous
    message with the same Message-ID.  (It is recommended that no
    Message-ID be reused for at least two years.)  Message-ID's have the
    syntax:

                     <string not containing blank or ">">

    In order to conform to RFC-822, the Message-ID must have the format:

                          <unique at full_domain_name>

    where full_domain_name is the full name of the host at which the
    message entered the network, including a domain that host is in, and
    unique is any string of printing ASCII characters, not including "<"
    (left angle bracket), ">" (right angle bracket), or "@" (at sign).

The syntax has also been refined in RFC 2822, to which RFC 1036 defers by
way of RFC 822, to require that the RHS be something that looks like a
valid domain name.

Since ":" is an illegal character in a domain name, I believe that INN is
right to reject such messages.

Note that some other servers, particularly transit servers, perform little
to no syntax checks on the message ID header, unfortunately.

-- 
Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>