However on CentOS 7, init was replaced by systemd. systemd would treat the MailScanner and sendmail process at one service, if you stopms or kill MailScanner, systemd will run "/etc/init.d/MailScanner stop" to stop the sendmail processes too.
Make the following changes to overcome this issue:
# mkdir /etc/systemd/system/MailScanner.service.d
create custom_script.conf with followings:
[Service]
RemainAfterExit=yes
# systemctl daemon-reload
Reference:
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/sect-Managing_Services_with_systemd-Unit_Files.html#brid-Managing_Services_with_systemd-Overriding_Unit_Mod
http://www.unix.com/man-page/centos/5/systemd.service/
RemainAfterExit=
Takes a boolean value that specifies whether the service shall be considered active even when all its processes exited. Defaults to no.