Great question! Think of it this way: your own machine acts as the server. So yes, in your scenario, the message waits on your machine until both sides are online at the same time. Once that happens, it gets delivered automatically. It works exactly like regular email, except your PC does the job instead of an external server. No middleman needed. In practice, if you leave PeerBox running, the overlap happens naturally, even for a few seconds. And if you really need guaranteed async delivery across very different time zones, you could just keep PeerBox running on a machine that stays on, like a small home server or a Raspberry Pi.