interesting mail problem

[Chip Rosenthal]

Chapter three of the continuing saga...
In part one, I mused about ripping out the SCO XENIX mail system.
In part two, I did so and replaced it with "free" software (Elm,smail,deliver)
In part three, we look at a strange problem introduced by the above...

One thing I did was write a quick /bin/mail which is similar to the
svbinmail.c distributed with smail 2.5, but simpler.  The idea is that
"/bin/mail" immediately execs either "/bin/smail" or "/usr/bin/mail", as
appropriate.  Although everything could go through "/usr/bin/mail", this
approach gets stuff directly into smail and saves a couple of execs.

Here is where things get interesting.  All of a sudden, the mail messages
from several of my cron tasks were getting messed up.  Sometimes part of
the message would be interspersed with the mail header, sometimes not.
I spent a couple of days trying to figure out why certain mail messages
failed and others worked, and trying to come up with a repeatable way of
causing the failure.

For example, when maps were unbundled, I would get something like:

	From news Sun Feb 12 00:31:43 1989
	Received: by vector.UUCP (smail2.5)
		id AA07128; 12 Feb 89 00:31:40 CST (Sun)
	shar: extracting u.usa.ny.2
	Message-Id: <8902120031.AA07128 at vector.UUCP>
	Date: 12 Feb 89 00:31:40 CST (Sun)
	From: news at vector.UUCP (USENET News Administrator)
	To: chip at vector.UUCP


	*************************************************
	Cron: The previous message is the standard output
	      and standard error of one of your cron commands.

Note that the "shar" message is stuffed in the header, but the "cron"
message is in the body.

Suddenly it dawned on me.  This problem only happens when the message
starts off with a program diagnostic.  You know:

	progname: some diagnostic message

Smail is treating these diagnostics as mail headers.  I haven't fixed this
yet.  I see a couple of approaches:

(1)  Throw away /bin/mail and let cron work through SCO's /usr/bin/mail.
     A giant step backwards.

(2)  Force a blank line or a mail header at the top output from my "cron"
     tasks.  Ugly.  This means mail messages even when there is output.

(3)  Handle the output directly inside the cron task rather than letting cron
     do it.  Kind of a pain in the neck.

(4)  Drop the XENIX cron, switch to one of the free ones, and fix it there.

I prefer #4, I think.  But #1 would be the easiest.
-- 
Chip Rosenthal     chip at vector.UUCP    |      Choke me in the shallow water
Dallas Semiconductor   214-450-5337    |         before I get too deep.