$ sudo apt-get update
$ sudo apt-get install libactionmailer-ruby 

libactionmailer-ruby is installed in your system.

Make ensure the libactionmailer-ruby package were installed using the commands given below,

$ sudo dpkg-query -l | grep libactionmailer-ruby *

You will get with libactionmailer-ruby package name, version, architecture and description in a table

libactionmailer-ruby package basic information: