Before, most Japanese company used PPAP to send files with email. PPAP is a jargon that protocol name in JAPAN. PPAP is an idea of "Sending crypted zip file with email and sending password of zip with next email".
Japanese company used the idea for security. But it didn't work well for security because of using same root sending crypted zip file and password.
So our Japanese company want to use BOX instead of PPAP. This idea is not collaborating function of BOX. The idea is "Sending files (or folder) URL of BOX to BOX users". When receiver want to download from the files URL, they have to login with BOX. So sender doesn’t need to send password on email anymore. For now, using collaborator function is too expensive to just sending files. The idea is very little, but most of the Japanese company would start considering to use BOX which have this function.