I am looking into migrating to Zimbra.
Current setup[mail received through courier-imap]:
Host: mailA [IP: 220.127.116.11]
mail handled by: mail.mailA
When mailA is down, its mail is handled by zimbraMailB [MX records setup]
Has accounts: a.b@mailA, b.b@mailA
Host: zimbraMailB [IP: 18.104.22.168]
mail handled by: zimbraMailB
Has an alias: a.b@mailA, b.b@mailA
How can I setup zimbraMailB to store messages destined to a.b@mailA, b.b@mailA in the aliases a.b@mailA, b.b@mailA when mailA is down?
How can I setup zimbraMailB so that once mailA is no longer in use to receive mailA's emails?
Your help is appreciated.