E-Mail（电子邮件）
链接
Postfix
Dovecot
新建邮箱用户且不允许本地登入
新建不可登入用户：
useradd -s /sbin/nologin stu1
useradd -s /sbin/nologin stu2
useradd -s /sbin/nologin stu3
修改用户密码：
[root@host-192-168-30-101 ~]# passwd stu1
Changing password for user stu1.
New password:
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: all authentication tokens updated successfully.
[root@host-192-168-30-101 ~]# passwd stu2
Changing password for user stu2.
New password:
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: all authentication tokens updated successfully.
[root@host-192-168-30-101 ~]# passwd stu3
Changing password for user stu3.
New password:
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: all authentication tokens updated successfully.