Templates:
- heartbeat_initial
- heartbeat_reminder
- vote_initial
- vote_reminder
- recipient_unlock

Examples:
  php scripts/send_test_email.php vote_initial csurbier@idevotion.fr
  php scripts/send_test_email.php heartbeat_initial csurbier@idevotion.fr
  php scripts/send_test_email.php recipient_unlock csurbier@idevotion.fr