Not difficult in terms of posts.
Pigeon holes
Scan names on letter
Put letter into pigeon hole
Letters can't recognise into another section
As for the mail
Program employee and is desk location
It has a map of the office floor plan
Mail will be sorted in pigeon hole
Pick up mal, take to location
Something like that?
If only it was that simple.
I can assure you that Honda certainly doesn't use old Asimos for such tasks, but there are robots that can and do DO such activities.
The letter sorting is done all the time by every postal service in the world more or less, the robot wont look much like Asimo though. In fact, one of the first real applications of Optical Character Recognition (OCR) was developed in the 50s for the US postal service and was why the numeric Zip codes were invented.
For mail delivery, this is a big challenge in robotics. You state that give the robot a map of the environment and it can deliver mail. The problem is, how does the robot know where it is in the map? The localization problem in robotics. Simply giving a map is not a solution, nor a requirement as mapping is also possible simultaneously, hence the SLAM problem.
With current technology this is perfectly viable (there are robot vacuum cleaners that no do real time SLAM).
The challenge is having a robot that an reliably locomote through real world environments. Emphasis on reliable and real-world. Asimo certainly doesn't have the reliability to go through a real office to be viable.
I know for a fact that the old Asimos are used for research by honda. My old lab had joint research with honda and Honda also demonstrated Asimo at my university.
But delivering mail is a chepa easy task for a minimum wage human.