Purchase rail tickets. Chengdu Airport.

For office, which office do you mean?
As I know, only a train ticket vending machine exists in the airport, so the email address may not exist.
I suggest you to book on this website and then you can pick up your ticket at the vening machine when you reach the airport.

Thank you kindly Ryan. You have saved me time and trouble arriving and talking to a machine WHEN I MISTAKELY thought that there was a manned office at the airport.
OK. So I purchase ticket for collection at the machine. Can you let me know early I can pre purchase tickets on this site? It will be too late to purchase at the station on arrival .
Again. Thanks very much. Dave

It is suggested to book 20 days before your departure date, so that you may get the seat or the sleeper easily.
You are right. It is too late to purchase the ticket upon your arrival at the station. If you book so late, maybe it is hard for you to get a seat.