With this App you can share files with the local MAPI-Client (e.g. Outlook Desktop, Thunderbird).

Please note, that applications like Outlook accept only one MAPI-request at the same time. These has to be processed/send before you share the next file(s).

Desktop Mail don’t control a mail-application.
Only a mail description is tranfered into the windows system by using a MAPI call. Windows forward this to the registered mail-application.