[TriLUG] backup email server

[Michael Hrivnak]

Dear all,

I've done a lot of research and work on getting a backup email server working, 
but I want to bounce some things off you folks first to make sure I haven't 
overlooked something.

Basically, email to an @hrivnak.org email address comes to my machine on a RR 
connection.  I want to have another machine on a different connection that 
will accept email for hrivnak.org if my server is down and relay it once my 
server is back in action.

Both machines are Mandrake 10.0 running postfix.  One is "hrivnak.org" the 
other is "somemachine at hrivnak.org".  Here is what I have set in main.cf on 
the backup machine.  I've left some things out, but these are the things I 
want reassurance on.

mydomain = hrivnak.org
mydestination = $myhostname, localhost.$mydomain, localhost
relay_domains = $mydestination hrivnak.org
delay_warning_time = 24

The rest are defaults.  I think this will make the machine relay mail to 
hrivnak.org.  Am I correct?

Now, help me out on what exactly goes on here.  A mail server tries to contact 
hrivnak.org and fails.  It instead sends to this backup machine, which 
accepts relaying.  Now I'm not so sure.  The mail sits in Que I guess waiting 
to be relayed.  How often does postfix attempt to relay it?  Do I have 
control over this?  Does it ever give up?  Where exactly does the email sit?

Thanks for your help.  You folks have already been tremendously helpful with a 
couple other issues this week, and I'm very grateful!

Michael