OT: Default email client

["Jeffrey Ratcliffe" <jeffrey ratcliffe gmail com>]

Hi all,

Apologies for the fact that this is some way off topic, but I can't
find the answer via Google:

A user has requested the option to send the PDF output produced by my
Gtk2-Perl application using the default email client.

Is there any way of digging out, firstly which desktop is being used,
and then which is the default email client? Then presumably each
client has its own (if at all) command line options for composing a
blank email with an attachment.

Or is it all much easier?

Regards

Jeff