Psi-IM - Psi-IM is a messaging program that is designed for the XMPP network.
AfterShip - AfterShip is the shipment tracking API for ecommerce businesses and marketplaces.
Gajim - Full featured and easy to use Jabber client
OnTime 360 - Cloud-based courier software with online order entry, route optimization, and dynamic tracking. The complete delivery software solution.
Empathy - Apps/Empathy - GNOME Wiki!
couriermanager - Try couriermanager! A software solution designed especially for courier companies management. Organization, efficiency and productivity!