SMTP und tunnelling shield: was sie gemeinsam haben
- Schritt 1. SMTP — wird verwendet in — E-Mail. Sending mail.
- Schritt 2. E-Mail — entwickelte sich aus — Postal service. Electronic mail.
- Schritt 3. Postal service — nutzt — Steam locomotive. Mail trains.
- Schritt 4. Steam locomotive — nutzt — Railway track. It runs on rails.
- Schritt 5. Railway track — wird verwendet in — Metro. It runs on rails.
- Schritt 6. Metro — nutzt — Tunnelling shield. Metro tunnels were built with shields.