“ Authentication failed. Please check your credentials.”is displayed when you log in to the QQ mailbox, how can I solve the problem??

I want to connect to South Korea using residential, but there is currently no way?

Update Sept. '23: Limits the approach lately, tells me I have to wait an hour because I reached my daily traffic limit.
I used the service always as a free user and his happened never before. I haven't changed my use in any way...
So... the description should be urgently changed.
Free users DON'T get UNLIMITED access any more!


Works mostly fine.
Only some websites won't work when I select to be connected through the USA.

总的来说还是不错的(但是服务器出问题时没有及时通知，让用户sad）