[lug] MX host question

[Chip Atkinson]

Greetings,

I had a question about MX hosts.  If one has 2 or more MX hosts
within a domain, do they all need to know the names of all the users?

If I have 2 hosts, but only one host knows all the users on the domain
machines, how do I ensure that mail sent to the aux. MX machine gets to
the main mail machine?

Thanks in advance.

Chip