$ sudo apt-get update
$ sudo apt-get install cyrus-pop3d 

cyrus-pop3d is installed in your system.

Make ensure the cyrus-pop3d package were installed using the commands given below,

$ sudo dpkg-query -l | grep cyrus-pop3d *

You will get with cyrus-pop3d package name, version, architecture and description in a table

cyrus-pop3d package basic information: