Have you ever tried to use the right click/Send option in order to send a file via Email? Have you ever got this error: 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.
Unfortunately, the Mail app does not support this function at this point. The only solution is to install a desktop mail program like (Mozilla Thunderbird, Live Essentials with Mail …).