I would like to recommend you secure application Zimbra to MBOX Converter Tool to move Zimbra file to MBOX. Various features are:

• This software is secure and protected that can easily move Zimbra file to MBOX and other file formats like PST, EML, EMLX, HTML, PDF, etc.
• This application securely move Corrupted file.
• This tool also move Corrupted file firmly and Meta properties email get move.

Read more: https://www.kdetools.com/zimbra/mbox/