.§§§ File

The §§§ file extension is associated with Pegasus Mail and used for Temporary files, used by the program, when parsing attachments and/or html files.

Those files should be deleted by Pegasus Mail, but are not. You can delete them yourself. When you do, make sure Pegasus Mail for Windows is not active.

How to open:

In vast majority of cases, users cannot access temporary saved data.

How to convert:

Temporary files are usually not meant to be converted to anything else.