QQ is a Chinese ISP that is showing up on more and more commercial lists in the US.
Delivery to QQ, particularly for senders outside of China, can be difficult. IPs allocated to regions outside of China are limited in the number of connections they can make and the number of emails per day is heavily controlled. Limits are as low as 1 connection per IP and 1 email per connection. Daily limits seem to range between 20,000 and 40,000 emails per day from IPs outside of China.
QQ does provide postmaster pages
QQ does not provide a traditional feedback loop
Whitelisting is available, but only open to companies with a Chinese business license and China-based IPs.
QQ does not use any commercial certification services.
QQ does not provide support for most senders. Some people have been able to contact postmaster by asking co-workers who are fluent in the local language to send mail to postmaster.