A customer has complained because he tried to contact me over a long period of time. His emails never got through and now I know why. He is from Singapore and his ISPs traffic is using China backbones. China has blocked my server so that is why his emails were not delivered.

In my opinion I am not liable here but it is the criminal Chinese government that caused these damages. They do not have a reason to block my IP. They just blocked an IP range and my IP is within this range.

You are certainly not liable, as it's nothing you're doing wrong. Since you can't do anything to resolve the problem, I would just not worry about it.

Could you post a link to your TOS?