> [...] and there are a tiny
>number of mailers that don't insert Received lines, so this is not
>perfect, but it is a good place to start if you can't idently the user
>by username alone.
Remember, folks, if you have any influence on any local Postmasters, if their hosts do NOT insert full, complete Received headers, PLEASE help by asking/begging them to consider fixing their configurations! It may not directly help them, but someday it may help you, in a situation like the one described here, where a mysterious bounced error results from a subscriber address being forwarded elsewhere...
Here's an example of a "complete" header. If you were trying to track why List-Managers-Digest subscriber "email@example.com" had turned into actual address "firstname.lastname@example.org" (say you were getting bounces from ornette even though no ornette address was on your list), this header would be crucial in tracing the forwarding path:
> Received: (from daemon@localhost) by prism.uchicago.edu (8.6.11/8.6.11)
> id MAA13692 for email@example.com; Mon, 15 Apr 1996 12:07:37 -0500
There have been times when I had to track down a mystery and the only useful clue I had was one of the components of such a header. Sometimes even just the Queue ID ("MAA13692" in this case) can help, since the mail system syslog shows the queue ID on the entries listing the incoming originator, and outgoing recipient, addresses.
I have just decided to begin assembling a "Postmaster Information" Web page <URL: http://www2.uchicago.edu/ns-acs/ckk/postmaster.html>, trying to collect ALL the information like this that an Internet Postmaster should know (including how to administer a mailing list server, PH directory server, etc.), into one place, since I've never seen it all collected before (if there already IS such a thing,specifically for the Internet Postmaster, please let us know the URL or the published book title! haven't looked at O'Reilly's Managing Internet Services yet for example).