Fwd: Question on standards for message ID

Russ Allbery rra at stanford.edu
Wed May 16 23:31:36 UTC 2001

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

                     <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/>

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