As the installer of LibreOffice I find that I can send documents via email quite happily. I use Thunderbird as my email client.
My partner, who uses Windows default email client, cannot; she receives the message
There is no email program associated
to perform the requested action.
Please install an email program or, if
one is already installed, create an
association in the Default Programs
control panel.
There does not appear to be any option in the settings that would control the email client for a user.