You can add to the your DNS zone configuration any number of mail servers (0,1,2,3 is the priority, it will try 0, then 1, then 2 ...): IN MX 0 mailUS.example.com. IN MX 1 mailCH.example.com. IN MX 2 mailBR.example.com. IN MX 3 mailUK.example.com. I don't know how to configure the backup mail server to send the backed up mails to the main server when it is up again.Oh, I forgot to say that the assumption here is that all possible internet connectivity with the US office is down. So there would be no way to basically repoint incoming mail to any other server.Ok, I guess you want to have a backup mail server for npc-usa.com and the backup partner could be vostok1.com or vostok.pt or any other: You have to have this configuration on your DNS zone at npc-usa.com: IN MX 10 smtp.npc-usa.com. IN MX 20 mail.vostok1.com. you will also have to configure the mail server at vostok1.com to accept mail relay for npc-usa.com. You don't care if your internet connectivity is down, any mail servers trying to send mail to you will query the DNS server at speakeasy.net, and will find that mail.vostok1.com also accept mail for npc-usa.com.
What you propose is very interesting. Perhaps the solution will be a little bit different though.
In the US we host mail.npc-usa.com (and smtp.npc-usa.com), mail.vostok1.com (and smtp.vostok1.com). The vostok1.com server is the one in question actually. The 2 are totally separate servers.
Now let's say for whatever reason the mail servers in our company are all down as there is no Internet connectivity with our office.
If I understand correctly I could set up yet another backup domain name: let's say vostok.pt.
Regardless of what I have set up internally, I would also have to inform speakeasy that any mail intended for mail.vostok1.com should also be sent to mail.vostok.pt? I would therefore have mail.vostok.pt pointed to the overseas operations mail server ip address? Would then any mail sent to mail.vostok1.com also be sent to mail.vostok.pt?
This is an interesting issue that I didn't know existed and appreciate any input.
Curtis