Inform user of new download

I have a client that wants to be able to upload files that are only viewable by a selected user or users per file. Which I gather your plugin should work fine for.

However he also wants an email sent to the users when they are granted access to a new file, is this something your plugin can do? and if so what add-on would I need to get this working? I noticed a few newsletter addons but it is not clear if I could get them to work this way.

Thanks for your help