indicator-messages software package provides indicator that collects messages that need a response, you can install in your Ubuntu 14.04 LTS (Trusty Tahr) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install indicator-messages
indicator-messages is installed in your system.
Make ensure the indicator-messages package were installed using the commands given below,
$ sudo dpkg-query -l | grep indicator-messages *
You will get with indicator-messages package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | GNOME |
| Package | indicator-messages |
| Version | 13.10.1+14.04.20140410-0ubuntu |
| Description | indicator that collects messages that need a response |
| Sub Section | GNOME |