The Zimbra Web Client is a graphical user interface (GUI) that includes windows, buttons, text entry, and mouse.
With a GUI that uses Internet browser technology to display and operate the user features, it is not always possible for the application to detect when you have done something that you might want to save.
Within Zimbra, the following rules apply:
If you are in the middle of composing an email message, and you click another portion of the Zimbra screen, you are prompted to save your work. You can subsequently find the message in your Drafts folder.
Reloading the Zimbra Web Client from the same browser window will continue your mail session, but you may lose any unsaved changes.