在Linux服务器（CentOS release 6.6）上配置好了sendmail后，测试发送邮件时发现有问题，检查sendmail服务的状态，发现其处于“sendmail dead but subsys locked”， 检查发现postfix服务也在运行。只需要将postfix服务停掉即可。为什么会出现这种情况呢？Something was occasionally causing the postfix service to start which then caused the status of sendmail to jump to dead but subsys locked. 两种似乎不兼容。
操作步骤：
1：检查sendmail服务的状态
[root@DB-Server ~]# service sendmail status
sendmail dead but subsys locked
sm-client (pid 22112) is running...
2：检查postfix服务的状态
[root@DB-Server ~]# service postfix status
master (pid 1777) is running...
3：停止postfix服务
[root@DB-Server ~]# service postfix stop
Shutting down postfix: [ OK ]
4：重新启动sendmail服务
[root@DB-Server ~]# service sendmail stop
Shutting down sm-client: [ OK ]
Shutting down sendmail: [FAILED]
[root@DB-Server ~]# service sendmail stop
[root@DB-Server ~]# service sendmail start
Starting sendmail: [ OK ]
Starting sm-client: [ OK ]
5：禁用postfix在reboot后自动启动
检查一下是否有设定 postfix 在 reboot 后自动启动
chkconfig --list | grep postfix
chkconfig postfix off
