Install monit on your server as per instruction available at

Restarting Services with Monit

Now create a file

vi /etc/monit/conf.d/qmail-send

With following content

check process qmail-send matching "qmail-send"
   start "/etc/init.d/qmail start"
   stop  "/etc/init.d/qmail stop"

Restart monit service

service monit restart

If all setup properly, you will be able to view qmail-send status in monit web interface.

To see status of the monitored services from command line, run

root@server10:~# monit status
The Monit daemon 5.4 uptime: 52m 

Process 'qmail-send'
  status                            Running
  monitoring status                 Monitored
  pid                               21380
  parent pid                        1
  uptime                            2m 
  children                          4
  memory kilobytes                  484
  memory kilobytes total            3824
  memory percent                    0.0%
  memory percent total              0.0%
  cpu percent                       0.0%
  cpu percent total                 0.0%
  data collected                    Mon, 25 Sep 2017 07:34:50

System 'system_server10.hostonnet.com'
  status                            Running
  monitoring status                 Monitored
  load average                      [0.23] [0.30] [0.36]
  cpu                               2.1%us 0.4%sy 0.7%wa
  memory usage                      2016848 kB [6.1%]
  swap usage                        0 kB [0.0%]
  data collected                    Mon, 25 Sep 2017 07:34:50

root@server10:~#