I believe that I have my installation troubles figured out, but I want to check before I break something.
I have Zimbra installed, via the 'simple' installation instructions, on a machine at domain.com.
In addition, mail.anotherdomain.com and the MX record at anotherdomain.com point to domain.com
anotherdomain.com is the domain for which the mail service is set up.
What I'd like is a backup mail server.
I plan to install just the MTA on domain2.com.
Then, update the DNS records for anotherdomain.com to point to domain.com 1st and domain2.com second.
I'd like to continue to receive mail, even if the main server at domain.com goes down. I understand that mailboxes would not be available unless and until domain.com went back up, but, if I understand correctly: if mail cannot be delivered to domain.com, then it will be delivered to domain2.com, which will hold onto it until domain.com is restored.
Will this work (the way I want it to?). Is there a better way? Can the secondary mail server (domain2.com) run apache if it is only running the MTA service?
Thanks for bothering with me.