Adding new email client

Hello!

I am wondering if it is (would be) possible to add a new email client 
program to the selection used by the "Send by Mail" tool?
I have Outlook but due to the known problem of not being able to send 
multiple images at once I would like to use another client. I know 
Thunderbird can do that but I am currently using the Betterbird fork of 
Thunderbird. So my question is if I can add this to the DK - when i use 
the "Send  by Mail" tool I cannot choose/add this as a new mail client 
binary.

Best regards,
Andrej