Individual email messages (.msg) can be extracted or in case of emergency recovered using any of the available Outlook recovery utilities or Outlook itself. For example the SysTools OSTRecovery solution can be used for OST to MSG conversion (recovery).
Convert Microsoft Outlook inbox off-line folder to Saved email message.
We have found 2 software records in our database eligible for .ost to .msg file format conversion.
Microsoft Windows software - convert ost to msg on Windows
An e-mail management tool distributed with Microsoft Office suite
Convert from ost file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned ost to msg. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A utility used to convert OST to PST/ MSG/EML files