[Unit]
Description=Send message on startup 
#and shutdown
After=network-online.target time-sync.target
#Before=postfix.service

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/usr/local/bin/systemd-email startup
#ExecStop=/usr/local/bin/send_stop_mail.sh
#ExecStop=/usr/local/bin/systemd-email shutdown

[Install]
WantedBy=multi-user.target