Multiple IP addresses for same host name in /private/etc/hosts?

Question

I have a corporate mail account (exchange 2007) that uses a self-signed SSL certificate. No matter what I do, Mail always complains about this when I connect. If I look at the details it always says the certificate name post does not match the dns name I used to connect.

I had the bright idea to add an entry in /private/etc/hosts that mapped the name post to the external IP of the server. This works beautifully and the certificate error is gone and everything works when I am out of the office.

The problem with this is that when I am in the office I need to access the server by its internal address, and the only way I could connect was to remove the line I added to hosts, or to change the IP from the external IP to the internal IP.

Now for the question: Is there a way I can format multiple entries in the hosts file for the same host name, but with different addresses? I know this is done with real dns servers, but it appears not to work in a hosts file. The idea is for the name lookup to return both IP addresses and Mail will fail over to the second address when the first does not work.

I know there is a setting in Mail for internal and external names for the server, but using this brings back the original certificate errors. After some thought, I also wondered what would happen if I make a second entry for the same name but using IPv6 instead of IPv4? Should have IPv6 some time later this year, and if I understand correctly you can have one name listed twice in hosts when one address is IPv6.