I have a group of users that are not part of the domains in charge of Zimbra that need to access shared resources with edit rights. They work for a sister company, and need access.
To make login painless for them, I'd like, if possible, to allow them to login using their e-mail address and password. I can authenticate them against their own Active Directory, so authentication is not the problem I have.
The problem is : how to make them login with email@example.com without having sisterdomain.com a Zimbra domain. I can't declare it as a Zimbra domain, because then Zimbra will consider the mails as local and try to leave them on the local server instead of routing it to the sister company's mail server.
I could make them log with some ID other than their e-mail address, so it's a little problem, but if there is an easy solution, I'd gladly take it!