在Linux服務器（CentOS release 6.6）上配置好了sendmail后，測試發送郵件時發現有問題，檢查sendmail服務的狀態，發現其處於“sendmail dead but subsys locked”， 檢查發現postfix服務也在運行。只需要將postfix服務停掉即可。為什么會出現這種情況呢？Something was occasionally causing the postfix service to start which then caused the status of sendmail to jump to dead but subsys locked. 兩種似乎不兼容。
操作步驟：
1：檢查sendmail服務的狀態
[root@DB-Server ~]# service sendmail status
sendmail dead but subsys locked
sm-client (pid 22112) is running...
2：檢查postfix服務的狀態
[root@DB-Server ~]# service postfix status
master (pid 1777) is running...
3：停止postfix服務
[root@DB-Server ~]# service postfix stop
Shutting down postfix: [ OK ]
4：重新啟動sendmail服務
[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后自動啟動
檢查一下是否有設定 postfix 在 reboot 后自動啟動
chkconfig --list | grep postfix
chkconfig postfix off