Re: [Exim] Force new (valid) Exim-style message id fromsyste…

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Auteur: Ralf G. R. Bergs
Date:  
À: exim-users ML
Sujet: Re: [Exim] Force new (valid) Exim-style message id fromsystemfilter?
On Wed, 12 Feb 2003 08:46:51 +0000, David Woodhouse wrote:

>On Wed, 2003-02-12 at 08:23, Ralf G. R. Bergs wrote:
>> No -- $message_id is the internal Exim "job number," the one you use e.g.

to
>> remove messages from the queue. It's not a "fully-qualified" message id.
>
>Ah, OK. That makes sense then, assuming it's sufficiently unique.


It IS "sufficiently unique" as described in Exim's specs:

<quote>
Every message handled by Exim is given a message id which is sixteen
characters long. It is divided into three parts, separated by hyphens, for
example 16VDhn-0001bo-00. Each part is a sequence of letters and digits,
normally representing a number in base 62. However, in the Darwin operating
system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36 is
used instead, because the names of files in those systems are not case-
sensitive.

The first six characters are the time the message was received, as a number in
seconds - the normal Unix way of representing a time of day. If the clock goes
backwards (due to resetting) in a process that is receiving more than one
message, the later time is retained.

After the first hyphen, the next six characters are the id of the process that
received the message.

The final two characters, after the second hyphen, are used to ensure
uniqueness of the id. There are two different formats:
</quote>

[...]
>> would generate illegal message ids (since I only have private IPs and
>> hostnames inside my LAN.) I finally managed to tweak it so that it does
>> generate valid message ids, but I thought it might be a more clever

approach
>> to have my mailserver generate unique and valid message ids.
>
>Using an RFC1918 IP literal wouldn't be too clever, I suppose -- but
>private hostnames are permitted, as long as they're unique. Isn't your


I think that private hostnames ARE NOT permitted. As message ID needs to have
a FQDN as the part after the "@," and a private hostname doesn't qualify as a
FQDN (because it is, by definition, not unique.)

>own internal domain nomenclature sufficiently unique? Is there really a
>chance of someone else naming their internal machines 'ralf.wg', etc.?


Absolutely.

Cheers,

Ralf


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