mail from: field question

[Lowell Gilbert]

Jim Bow <jimbow at darq.net> writes:

> I have a small shell script that does a backup to a usb drive and
> emails the results to a set of people. The script is triggered from
> devd (upon drive attachment) and runs as root.
>
> The problem is that the mail report is sent from an active system user
> and not user root. The user the mail is sent from is not referenced in
> the script. The mail line looks like this:
>
>    cat $LOGFILE | mail -s "backuptousb report" recipient at one.net
>
> I find this rather confusing since I was expecting the email to be
> sent by the user running the script. How can this be?
>
> A little research told me that this may be because of something called
> envelope-from, but I found little explanation of what that actually
> means. Anyone have any suggestions?

The answer will probably depend on the MTA you're using (which you
didn't mention, so it's probably sendmail), but checking a couple of
simple things first will help ensure you're at least on the right
track.  Run the script from the command line, and in particular just
call mail the way the script does.  Make sure the results are the same
(if they're not, the MTA isn't the problem).  Then, look in the mail
logs to see what they tell you about the message.