Social Messaging

I thought of this idea for a social service that works like a collaborative email that's authenticated on a server and allows you to manage different groups to share different content with.
First of all you compose a message with any kind of webpage content you would like, pictures, links, attached files, whatever. And you choose what groups to send the message to.  Example:

Then a message is sent to the server to make sure whoever you are sending it to has put you in a list of people they want to receive messages from (you can only get spam from people you've authorized!):

If it is verified, the message goes to the person you're sending it to's inbox where they can see new messages:

The neat thing is on each message it gives everyone the message was sent to a place to edit the message, the server will send the update to everyone the message was originally sent to:

The app provides an interface to quickly add and remove different contacts from different groups:

There's also an interface for seeing who has sent you a contact invite or for you to send contact invites, also to remove someone from your contact list. Then they will no longer be able to send you a message. To make a connection between two people both people have to confirm by entering their password which the server verifies. 

So it's pretty simple the server I make doesn't even have to store anyone's files except temporarily it merely keeps a database of who is authorized to send messages to whom and sends the message along. I feel like it combines the best aspects of email, google+, facebook, and google wave. 

UPDATE 1:

I finished the message editing part of the program here are a couple screenshots:

Here I'm viewing a message about fire and I've filled out a comment including a picture of a bucket of water.

When I click submit it adds my comment to the main message: 

So so far so good, next is the part of the program for selecting different messages. 

Update 2:

Now I've got the main message selection window done. When you click on one of your groups/person on the left it will only show you messages from anyone in that group or from that person.