$ perl resmtp.pl \
  [-d|--daemon] \
  [-h|--host <listen_host>] \
  [-p|--port <listen_port>] \
  [-t|--timeout <timeout_in_seconds>] \
  [-b|--blackhole] \
  [-f|--from <[email protected]>] \
  <[email protected]>[,<[email protected]>,[...]] [<smtp_host[:port]>]

# cat <<'EOF' > /usr/lib/systemd/system/resmtp.service
[Unit]
Description=resmtp Service
After=network.target

[Service]
Type=simple
ExecStart=/usr/local/bin/resmtp.pl --host 127.0.0.1 --port 25 [email protected]
Restart=on-abort

[Install]
WantedBy=multi-user.target
EOF
# systemctl enable resmtp
# systemctl start resmtp