[cobalt-users] Stupid secondary MX question?

["Rick Highness" <rick@xxxxxxxxxxxx>]

Gentlepeople:

I've been searching through the archives, and can't quite seem to find
an answer to my question. 

I have two RaQ550 boxen (Thanks, Gerald, you ROCK!).  I have one
configured as my production server and the other as my development (aka
hot backup).  If I want to have the development box accept mail for one
(or several domains) in the unlikely event that my production box goes
down, how do I do it?

This is what I have done:

On the production box: I have a MX record set with delivery priority set
high which points to the production box.  I have a second MX record set
with delivery priority set low which points to the development box.

On the development box: I have relaying allowed for the production box.

When I shut down sendmail on the production box and send an email to
someone on the production box, the development box gets the message
(like it is supposed to) but replies with: "Relaying denied.  Please
check your mail first or restart your mail session."

What am I missing?

Thanks for ANY help you can give me!

-Rick