Here I will show you how to add a new email account using SSH.
In this example we will be adding a user named Joe to the domain brightlemon.com
useradd -s /sbin/nologin joe passwd joe
Enter a password for joe. You will be prompted to enter it again.
Press [INSERT] to switch vi to edit mode and enter the following at the bottom of the file.
Press [ESCAPE] and type
before pressing [ENTER]. This will save the file.
You then need to postmap your changes.
Restart postfix with the following command. Depending on your server configuration one of the following 2 commands will work correctly.
service postfix restart /etc/init.d/postfix restart
The email to firstname.lastname@example.org is now configured correctly and can be connected via POP3