> Can you tell me what you mean by flood-fill?
OK, imagine a load of servers. Each is connected to some (not all) of the others, and they all peer messages to each other.
A -- B -- C -- D
| |
E -- F -- H
|
G -- I
A message M is sent to one (say A). B asks A "have you got any new messages?" (or it might be A pushes them onto B) and A replies with M.
From B, M is sent to C and E. From E it is sent to F and G. Eventually it gets to all the servers on the network.
I envisage that each message would have a unique ID consisting of a cryptographic hash of its contents and timestamp.