I would like to suggest you secure software Zimbra to Office 365 Converter software to migrate Zimbra file to Office 365 account. This application convert Zimbra TGZ file to numerous file formats such as PST, EML, EMLX, HTML, OLM, NSF, MBOX, and etc. This application also directly migrate Zimbra file to Office 365 and Exchange Server account.

Read more: https://www.kdetools.com/zimbra/office-365.html