Customers can safely log into their personal account to consult their current and past orders, among other useful functions, at any time.
Their files are saved and available at all times.
It is also from this secured area that your customers can request more complex quotations and/or send large files without having to use a specialised service or a FTP server.
Each of your customer's contacts have their own secured access. The rights hierarchy determines if they can or cannot access documents, current projects, and collaboration requests.
These features will allow you to retain your customer base as they will appreciate your absolute transparency.