> Bear in mind that the mail command isbasically a wrapper for sendmail
> when used thus:
> 
> echo some messages | mail -s 'some mail' [EMAIL PROTECTED]
> 
> If [EMAIL PROTECTED] cannot he reached immediately, where does the mail
go?

The command exits with a non-zero return code, and the application
invoking it is required to cope with the error and try a different
method of signaling a problem. If it doesn't cope, the message is lost. 

Remember the basic assumption was that he *didn't* want to run a full
MTA all the time. Starting with that assumption, you have to give up
some of the niceties of a full MTA daemon, like queuing and automated
retries, because there isn't any process there to DO the queuing or
retries. If immediate delivery fails, your application has to make the
call on what to do about it -- the MTA isn't there to defer things for
you. 

> If you have a working relay, fine, but if someone tripped over the
wire,
> what then?

That's precisely the argument for installing a smaller, less complex,
less resource intensive full MTA (like exim/postfix) running in daemon
mode in place of sendmail OR (better yet) not relying at all on a
complex system like email for alert notifications, but that's not what
he wanted. 

If you run your MTA in non-daemon mode, one consequence of that decision
is that your smarthost better be more reliable than you are if you want
email notifications to work reliably. That's one of the tradeoffs for
not consuming the resources of a full queuing MTA on each guest. 

Personally, I'd log stuff like that to syslog using logger rather than
using mail. Scales better, is a lot lighter weight than any of the MTAs
even in non-daemon mode, allows concentration/correlation of automation
and distribution of event notifications, and most of the good system
management tools already read and parse syslog output without inventing
any new wheels. It's also a lot harder to break syslogd.conf in stupid
ways than *any* of the MTA configuration files.

-- db

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