The problem is Microsoft against the rest of the civilized world. They have their so-called Uniform Naming Convention that is intended for use within their walled garden client/server realm and doesn't play nice in shared platform environments.
Microsoft:
file:///C:/Users/someuser/desktop/thisfile.txt
\\servername@SSL@443\Share Name\Folder Name\file.txt
UNIX (macOS) and Linux
file:///Users/someuser/Desktop/thisfile.txt
https://servername:443/Share%20Name/Folder%20Name/file.txt
smb://servername/Share%20Name/Folder%20Name/file.txt
So, without some namespace converter from Microsoft UNC to common sense, you cannot send emails to someone with a Microsoft UNC format that is receiving Mail on UNIX or Linux and have it just work without requiring conversion to a format that the current platform understands.
A converter to do this is not pretty, or simple to code.