Accepting a message
Grand-child process
- Waits for ìHELOî or ìEHLOî command
- Waits for ìMAIL From:î command
- Creates queue files in /var/spool/mqueue
- Waits for ìRCPT To:î command(s)
- Waits for ìDATAî command
- Waits for ì.î (on a line by itself)
- Writes the message to the mqueue
- Makes initial delivery attempt, and quits