Drag & Drop Email Creative Builder

We require a Drag and Drop feature for our email platform that will build a HTML email using 'content blocks'. We would like the user to be able to drag blocks from a menu to build their emails in HTML. This feature can be built in your choice of front-end web technology. The feature would enable users without HTML knowledge to design well-built, good looking HTML emails to send to their subscribers. The “Drag and Drop Editor” should be set out across the full screen and should be a simple design and intuitive. It should include an email template 600px wide and a maximum height of 3500 px with a basic “header, body and footer” design. There should however be more than one template to choose from using various lay-outs. The size of the email should not exceed 64GB and the feature should include an area where the user can create a text-only version of their email. When a ‘block’ is selected it should highlight (either in another colour or it ‘jumps’ from the menu) and change the cursor from an arrow to a drag cross-arrow. When dragged across to the template it should outline where the block would sit in the template. When adding a photo, you should be able to select from the Image Manager (A section within the system where users can upload and host their images) or can upload by selecting from their documents. We would also like to include Aviary into the system which is a photo editing suite. This can be added in the Image Manager or in the Drag and Drop editor ie; when you select an image to add it asks you if you would like to use the photo editing suite and then you can edit your image before you add to the email template. When the user is creating the email, it would be ideal if the system could tell the user to add more text to the creative if text falls below 50% to ensure image to text ratio is good. Once the user has finished building their HTML email there should be a Text Only Generator that pulls all text and links and creates a text only version of the email. The user should be able to edit the text only version. If you could like more information including a rough spec please get in contact and we can send across any information you may need. Otherwise please find a rough spec attached. Thanks!