If you are technically inclined, you may also manually import OST files into Zimbra. Users must convert their Outlook OST files before they may import PST files into Zimbra. Converting manually is difficult and prone to errors. Because of this, you can use a third-party application such as MacProTools  OST to PST Converter for Mac to import Outlook OST files into Zimbra Desktop. This software makes it simple to import an OST file into Zimbra Desktop while preserving all of the data. All Mac versions are compatible with the application. You may also download a free trial version of the tool to learn more about its features.