Round Robin Mail Exchangers

Would it be advisable to create an A record that resolves to multiple IP
addresses such as :

mailer 10 IN 192.168.1.1
mailer 10 IN 192.168.1.2
mailer 10 IN 192.168.1.3

....then add 'mailer' as an MX record for several hosts that wish to
receive mail? This solution would allow me to make changes to the mail
exchangers quickly, and in one location, without editing the records of
each host it was added to. The alternative is to add each of the three
mail exchangers to each host individually. I have about a hundred that
need to be changed, and may need changing again in the future.

Another related question, if the sender resolves the mail exchanger to
192.168.1.1, and it happens to be down, would it try again or would that be
it? It occurs to me that listing each of the mail exchangers individually
would result in each one being tried separately until it succeeds. Or have
I missed something!?

-Mike