https://support.kucoin.com/hc/en-us/articles/360003181794-Why-KuCoin-KYC-
According to that article, KYC is not compulsory but it will help you to recover back your account in case if you lose your login details.
I used this exchange when they launched and I deposited and withdraw successfully without any issues but after that didn't do more trades on this exchange yet.
You have a limit to withdraw upto 2BTC without KYC.
What is the reason of invalid address can you help me. thanks
Where do you send address? MEW or other exchangers?
Maybe you can create again the address and try to send in a few minutes.
I was wonder why my ethereum address is invalid when sending ethereum to my ethereum address from Kucoin but after using metamask then generate ethereum address I use it and it works fine?