Backup MX - Again

Question

Greetings all.
Firstly let me apologize for my ignorance of the postfix config files. I humbly beg forgiveness.
I am trying to get a backup MX configuration running.
Yes, I have read "STANDARDCONFIGURATIONREADME.html#backup". It is unclear, and I am still confused.
For example. The holy tome states that:
"When your system is PRIMARY MX host for a remote site you need the above, plus:
18 /etc/postfix/main.cf:
19 transport_maps = hash:/etc/postfix/transport
20
21 /etc/postfix/transport:
22 the.backed-up.domain.tld relay:[their.mail.host.tld]"
I hate the example domains in this passage. I presume "their.mail.host.tld" is the name of the server that is the backup MX, whereas "the.backed-up.domain.tld" is the server that is the primary MX. Is this correct? If this is the case, why would they provide the BIND example that calls the backup MX "your.machine.tld." then switch to calling it "their.mail.host.tld" in the postfix example? I must be interpreting this totally wrong.
Furthermore the holy document says:
"Important notes:
Do not list the.backed-up.domain.tld in mydestination."
Again, the Gods have been unclear. The document states that the previous two examples are BOTH meant to be included in the main.cf of the Primary MX. So if I'm not supposed to list backed-up domains in $mydestination, how am I supposed to define my server aliases? Does this "Important Note" not apply to the Primary MX .cf?
I've done my fair share of modifying config files but Postifix's Backup MX is baffling me. Could someone please PLEASE help clarify? Even a link to a more descriptive and explanatory document would be much appreciated.

Answer 1

Hi there,
No, you're exactly right.
My copy of the O'Reilly publication: "Postfix: The Definitive Guide" arrived in the (real) mail today. Once again, this marvelous publisher has put out a book that exposes a complex technical subject to be really quite simple when it's explained by someone who can communicate effectively.
Someone dropped the book on my desk around 10AM. By 2PM I'd already double-checked my configuration and tested to make sure that backup transport for my domain was functioning correctly, while prohibiting an open relay situation. It was really handy to be able to check the configuration by Telneting into port 25.
Thanks to Kyle Dent for writing this excellent guide and demystifying an easy to use and well-designed program.
http://www.oreilly.com/catalog/postfix/