  We describe HTTP Mailbox, a mechanism to enable RESTful HTTP communication in
an asynchronous mode with a full range of HTTP methods otherwise unavailable to
standard clients and servers. HTTP Mailbox allows for broadcast and multicast
semantics via HTTP. We evaluate a reference implementation using ApacheBench (a
server stress testing tool) demonstrating high throughput (on 1,000 concurrent
requests) and a systemic error rate of 0.01%. Finally, we demonstrate our HTTP
Mailbox implementation in a human assisted web preservation application called
"Preserve Me".
