I am close to my migration to zimbra (from courier-MTA suite). at the moment, we are using Thunderbird as our mail client. All users can receive email to multiple domains : olddomain.com and newdomain.com for example.

newdomain.com will be my default domain and olddomain.com will be a Domain Alias.

We would like to move from thunderbird to the zimbra web client. Is there a way to choose olddomain.com as the sender domain ? If so can it be done from the admin console ? This is very easily done in thunderbird, but I cannot find a way to set the sender domain adresse to the Domain Alias.

Why I want that ? The company will change this name and domain shortly. I will setup zimbra domain for the new one (so no need to change zimbra default domain later) BUT before the change the old domain must be the default.