Forward mail to external mail server and from external mail server back to zimbra
I would like to set up Zimbra at home to test drive. However, since it will only be used during the day I thought of shutting down the server every night. Because of this and other reasons I was wondering if I can use my existing mail server to forward incoming messages to Zimbra and that Zimbra can forward the messages to the existing server.
I am not an expert on this so I was wondering first of all is this possible and more generally how does it work in practice.
Suppose that current email is @existing.com which is handled by the existing mail server. What is Zimbra using? I suppose you have to have a @test.com for Zimbra in order to work with it since it is all based on email, right? If so does this mean that you have to have 2 mail domains -one used for Zimbra plus the one used currently on the existing system-?
When I give person A a Zimbra account email@example.com and that person wants to sent an email using his existing email account firstname.lastname@example.org that person should be able to sent out of Zimbra to his existing account where it is converted from email@example.com to firstname.lastname@example.org before sending out.
Since Zimbra will be down overnight I want to let email for person A to be processed to email@example.com where the server holds the email and once Zimbra is online forward the message to A's Zimbra account firstname.lastname@example.org
Hopefully this will work in some way or another.