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At 19:17 20/05/2003, you wrote:<br><br>
<blockquote type=cite class=cite cite><font size=2>Sorry, now that I look
at it a little closer, I'm thinking of the ESMTP id as listed in the
received headers.</font> </blockquote><br>
I think the answer you are looking for is "60 years".<br>
Old versions of sendmail used a primitive id (i.e. what is used as the id
in the filename in the queue), which would repeat. So they changed it to
use a system that would be unique over a period of 60 years (which has to
be enough, surely :-)<br><br>
<br>
<blockquote type=cite class=cite cite><font size=2>-----Original
Message-----</font> <br>
<font size=2>From: mikea
[<a href="mailto:mikea@mikea.ath.cx">mailto:mikea@mikea.ath.cx</a>]</font>
<br>
<font size=2>Sent: Tuesday, May 20, 2003 1:58 PM</font> <br>
<font size=2>To: MAILSCANNER@jiscmail.ac.uk</font> <br>
<font size=2>Subject: Re: DNS Cache and Sendmail Msg-Id</font> <br><br>
<font size=2>On Tue, May 20, 2003 at 01:31:25PM -0400, Derek Winkler
wrote:</font> <br>
<font size=2>></font> <br>
<font size=2>> Couple of kinda off topic questions...</font> <br>
<font size=2>></font> <br>
<font size=2>> Is setting up a caching DNS server for the MailScanner
machine a good idea?</font> <br>
<font size=2>> Not sure how this would effect RBL lookups.</font>
<br>
<font size=2>></font> <br>
<font size=2>> How unique is the sendmail message id, is it unique for that day or until</font> <br>
<font size=2>> the process ids rollover or some other method used? Searched the internet</font> <br>
<font size=2>> for this but couldn't find anything.</font> <br><br>
<font size=2>Done properly, the caching DNS server will retain records for their</font> <br>
<font size=2>TTL, so that you won't have to go all the way to DNSbl server each</font> <br>
<font size=2>time you look up, e.g., flowgo.com. Unless, that is, I'm much</font> <br>
<font size=2>mistaken.</font> <br><br>
<font size=2>The sendmail message ID is intended to uniquely identify the message</font> <br>
<font size=2>in the universe of all possible messages sent by all sendmail MTAs.</font> <br>
<font size=2>It may even succeed at that. Certainly the date and time, sendmail</font> <br>
<font size=2>process ID, and so on, are encoded in the 8.12 Message-ID -- down to</font> <br>
<font size=2>a very small quantum of time. IIRC, earlier sendmails used a similar</font> <br>
<font size=2>method, but the quantum was larger. Again, that's the way I understand</font> <br>
<font size=2>it, but ICBW.</font> <br><br>
<font size=2>Here's a randomly-chosen Message-ID from my system:</font> <br>
<font size=2>Message-Id: <200305201731.h4KHVapE058947@mikea.ath.cx></font> <br>
<font size=2> <date-->time moretime<pid-> machinename</font> <br><br>
<font size=2>--</font> <br>
<font size=2>Mike Andrews</font> <br>
<font size=2>mikea@mikea.ath.cx</font> <br>
<font size=2>Tired old sysadmin since 1964</font> </blockquote></body>
<br>
<div>-- </div>
<div>Julian Field</div>
<div><a href="http://www.mailscanner.info/" EUDORA=AUTOURL>www.MailScanner.info</a></div>
<div>Professional Support Services at <a href="http://www.mailscanner.biz/" EUDORA=AUTOURL>www.MailScanner.biz</a></div>
MailScanner thanks transtec Computers for their support
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