Build a website that allows our customers to make email newsletters

Hi We want to make a site for our customers that allows them to build email newsletter with the exact same functionality as this editor here: [login to view URL] However we want the following additions and make it more dynamic and use a database. We would have multiple users per client, and each client should only be able to access their own templates and campaign (a campaign is a completed template). - create / Save / edit / delete a campaign - View all campaigns associated with a single client - Export to mailchimp + other ESP's - Right hand menu allows the addition of new modules from a content library (drag and drop interface) - Client has access to multiple templates (which they are assigned to) - Change tracking - so when they save it says each version so they can revert to it if they want - login & password for the entire site Admin section - Add new templates for a specific client or everyone - see's all clients campaigns and templates - create user accounts - Manage the website Please post examples of relevant web applications that have the same sort of functionality. The final solution will be hosted by us - our preference is PHP and MYSQL. We will be expanding the functionality over the next year so will be an ongoing relationship.