$ sudo apt-get update
$ sudo apt-get install courier-authdaemon 

courier-authdaemon is installed in your system.

Make ensure the courier-authdaemon package were installed using the commands given below,

$ sudo dpkg-query -l | grep courier-authdaemon *

You will get with courier-authdaemon package name, version, architecture and description in a table

courier-authdaemon package basic information: