Convert the OST file into an EML file without losing the data. Then I would like to suggest the most professional tool like Data Recovery Freeware OST to PST converter. This enables you to convert the OST file into many other file formats. With attachments and without attachments. Moreover, this tool allows you to transfer the OST file to Thunderbird, Office 365, Gmail, Yahoo, etc.
It's important to remember that EML files are regular email files that contain a single email message, whereas OST files are usually connected to Microsoft Outlook and are used for offline access to mailbox data. If you wish to convert OST to EML, use the expert tool mentioned above instead of the manual method. The most sophisticated and effective tool for exporting OST files to EML format is the TrustVare OST File Converter Tool. Users can convert OST files to EML file format without installing any additional software. Users can convert their OST files into several different file formats, including PDF, MSG, MBOX, TGZ, EML, and EMLX.