Question : Practical Modern Sendmail Configuration (Info Question)

This is an informational Question that I'll have the Mods PAQ so it'll be in the solutions DB. (Note to Mods: I'll be adding material for several days, probably, so please wait)

Other Experts should feel free to reference this Question if doing so helps them answer another Question. So that credit may be given where credit is due, please provide Askers with pointers to this Question as opposed to copy-n-paste. Askers who desire to create a "Points for PsiCop" question should still award points to the other Expert who directed them here.

Unless otherwise noted, the book/chapter/page references are to _Sendmail_3rd_Edition_ by Bryan Costales, ISBN 1-56592-839-3, available at your fave local bookstore or online. At over 1,200 pages, it can be an intimidating reference, but once you learn your way around, its a good resource for the sendmail admin.

In this Question are several types of resources:

       - annotated sendmail.mc files
       - sample sendmail database files
       - helpful maintenance scripts

A few assumptions have been made for these materials:

        0) sendmail is already appropriately-compiled for your system, is properly installed, and runs without choking
       1) a modern version of sendmail is being used (v8.12.10 or later; latest as of this writing is v8.13.3); if you're running an older version, its outdated, probably  
                 vulnerable, and shouldn't be connected to the Internet
       2) sendmail is being run on a UNIX, Linux or UNIX-like (e.g. AIX) system
       3) sendmail has been compiled with Berkeley DB (http://www.sleepycat.com) support
       4) the production mail system configuration files and databases are stored in /etc/mail
       5) the admin has access to the m4 macros appropriate to their sendmail version  (as an example, the typical Sun supplied-with-Solaris version of sendmail lacks the
                m4 macros needed to use the information below)

If your system varies from these, then:

      0) Building and installing sendmail can very significantly by platform, and so is out of the scope of this informational Question
      1) If you're not running a modern version, then STOP - go get and install a modern version, then return here
      2) If you're running sendmail on Windoze or similar brain-dead OSes, you may be able to interpolate a lot of this info to your system, but I'm not responsible for
               anything that breaks....get a real OS
      3) Berkeley DB support is not an absolute must-have; you can use "hash" in place of "dbm" in the appropriate lines in the configuration files and scripts below and it
               should work with *most* environments
      4) Locations other than /etc/mail are, of course, just dandy; don't forget to tweak the files/scripts as appropriate
      5) If your vendor-supplied version of sendmail is old/outdated or doesn't include all the parts, complain to your vendor, and then go get the sources and build it so you
               have all the parts

And finally, don't forget to create a backup of your original sendmail.mc and/or sendmail.cf (and any support files or databases)  *before*  making radical changes.

So, let's go to it.

Answer : Practical Modern Sendmail Configuration (Info Question)

Submitted to PAQ with points refunded (500)

DarthMod
Community Support Moderator