We are working with an ISV who creates an email client. The following is defined in the .desktop file shipped in their snap:
Their mail client calls
xdg-mime query default x-scheme-handler/mailto to see if it’s the default mail client / change that setting. They are not able to call that from within the Snap of their application. Not being able to call
xdg-mime means the app won’t be able to tell if it’s the default mail client or change that setting.