Zimbra autodiscover configuration
When autodiscover is correctly configured for your domain name, your email client will autodiscover the necessary server settings in order to send and receive email – all you have to provide is your email address and password.
The details for how to configure this can be found in the Administrator portal > Support and Resources > Zimbra help.
Please see this Zimbra wiki article for full details:
Autodiscover for Outlook, Exchange Activesync and Exchange Web Services