There are multiple third party tools available on the internet; you just go with the right solution and that is Vartika Zimbra to PST Converter tool when I required same issue and got accurate result. You can export Zimbra Mailbox between components like emails, calendars, tasks, notes and briefcase. It is a Windows utility, supports Wins 10/8 / 8.1 / 7. This Software also gives you free demo versions which you can export 30 email per folders.
