You can use Commercial software like KDETools Zimbra to Office 365 Migration tool.
Several features are:
• Quickly transfer Zimbra file to Office 365 without facing any hassle.
• This tool simply migrate Zimbra file to Office 365 and Exchange Server without any hassle.
• This software also migrate Zimbra files to Office 365 and other file formats such as PST, MBOX, MSG, EML, EMLX, PDF, HTML, etc.
• This application easily migrate Zimbra file to Office 365 without losing data.
Read More:
https://www.kdetools.com/zimbra/office-365.html
