You can use third party tool like Zimbra to PST Converter that can quickly transfer Zimbra file to PST File without facing any hassle. This software also convert Zimbra files to PST, and other file formats such as MSG, EML, EMLX, PDF, HTML, etc. It extracts all the essential email components like To, Bcc, Cc, Sent, From, Received, Attachments, etc.
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https://www.kdetools.com/zimbra/