First thing you need to consider, run Outlook Scanpst.exe File with .pst File may be it will help you to find your missing email if this process is not work for you then no need to worry, search on Google Outlook Emails Recovery software, there are many companies providing a software with free trial version. First try the demo version of software to recover email after seeing the preview of recovered data then purchase the software. Here are some well known Data Recovery Companies
Recoveryfix for Outlook Email Recovery
Kernel for Outlook Recovery Tool
Stellar info
Data Doctor
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