[NTLUG:Discuss] Secondary Mail Server

[Jack Snodgrass]

On Fri, 22 Aug 2003 09:19:12 -0500, Rev. wRy wrote:

> I recently got a second box to use as a secondary mail server for one of 
> my domains, and have a question as to the setup.  Recently, my primary 
> server went down, and the secondary box did it's job and caught all the 
> mail, but it didn't forward to the primary box when it came back up.
> 
> 1)  What needs to be configured to make this happen automagically in 
> sendmail?  I have a feeling I borked an entry in my local-host-names 
> file, but I'm not sure.
> 
> 2) I have created the virtualuser table with local users on the 
> secondary box mapped to the users on the first box in this fashion:
> 
> localuser1	localuser1 at primary.mailserver.com
> 
> Is the above the way that should be handled?
> 
> TIA-
> Ry


Here is how it should work... ( you should not have done #2 above ) 

say that you have a primary mail server 
mail.primary.net ( 172.16.14.1 ) 
and as a backup mail server
mail.backup.net  ( 172.16.15.1 ) 

so you set up your MX records like:
mysite.net  in mx  5 mail.primary.net
mysite.net  in mx 10 mail.backup.net

if mail.primary.net is down, then mail will go to mail.backup.net
instead. As long as mail.backup.net doesn't have mysite.net in it's
local mailer table, then the mail will be queued in the mail queue and 
every 'x' minutes mail.backup.net will attempt to send the mail on to
mail.primary.net automatically.

mail.backup.net uses the MX records and determines that it is supposed
to send mail for mysite.net to mail.primary.net so it will.... that is 
as long as you don't configure mail.backup.net to think that mysite.net
mail is 'local' for that server. 

jack