Mail Tracking tracks the mail through the postal system down to the local post office level. This is not delivery confirmation / proof of delivery but is still a very usefull tool.
By following the flow of the mail follow-up e-mails or telemarketing calls can be better timed to coincide with mail delivery. Response expectation can be planned and resources allocated based on mail receipt. Postal delays can be flagged so information is available to better respond to quetions from expected recepients.