This project is a fork from the original Dropbox package from the University of Delaware (not to be confused with the service provided commercially at www.dropbox.com, which is a totally different thing). It is released under the GPL.
I have added several security features so it cannot be used to spam you, which is very easy in the Delaware code. The Delaware code never checked that your email address was real, nor that it was your address. So you could trivially fake the sender of Drop-offs. And driving the whole site could be automated as it did not check that a real person was using the site, and not a program spamming it.
I have also added all sorts of features such as upload progress bars.
I have totally refactored the code so that all the PHP "business logic" and the user interface are completely separate. This makes upgrades enormously easier when you have customised the web interface for your organisation, as you don't need to touch the PHP code at all to change the user interface.
You can now also send requests for drop-offs which is very useful in any organisation providing technical support to customers where they need customers to be able to send them files, without the customer needing to know anything other than the files they are to send. This is designed so that it can be integrated into any existing support ticketing system so that the up-loads go straight into your ticketing system and the files are added to the ticket's work log.
I have completely overhauled the user interface. The new interface is a fresh concept and looks almost nothing like the original interface written by Delaware. This has been professionally designed and implemented by a very good web user interface designer whom I have paid.
There is now a sibling package shipped in it called "MyZendTo". This provides a simple web-based filestore for your users, complete with per-user storage quotas, which they can use instead of systems such as Dropbox in which you give the operators of Dropbox full access to all your data and in which you cannot guarantee where your files are stored, not even which continent, which can have a large impact on the privacy of your file contents.
I have done an awful lot of work on the original Delaware code, it is now a very distant relative of the original.