- Never touches disk - did away even with checkpointing!
- Has its own simple smtp server to receive connections
- Uses adaptive forgetting as a scaling tool
- Deliberately manages smtp session length -- takes longer to accept mail when the server isn't busy, to slow spammers down, but goes fast when the server is loaded because it needs to. wow. Points for the idea, 10x score for actually implementing it :)
- Optimized for "survival" above all other criteria
Well worth reading the whole thing through on the mailinator blog, there is is much wisdom here...