Gmail was completely blocked in China
A few month ago, web version Gmail was blocked by the GFW (Great Fire Wall), so you can not use Gmail on your browsers unless you change your Hosts file to define a specific IP address for Gmail. but there was another way to use Gmail in China back in those month, you can use IMAP and POP3 to receive Gmail in China, in English, you can use Gmail via Email APP on your mobile device and some desktop software on your PC or Mac with no problem.
But since Dec 26.2014, the IMAP and POP3 protocal were blocked in China, the GFW blocked the IP address of Google’s IMAP and POP3 service, so there is no direct way to access Gmail in China right now, technically, if you know Google’s another IP address of the IMAP and POP3 service, you can update the IMAP and POP3 setting in your APP or software to access Gmail, but i am pretty sure 90% people don’t know how to find the new IP address and how to update their IMAP and POP3 settings
So, the best way to resolve the problem is using private VPN service, once you connected to VPN server, you can use Gmail directly, just like nothing happened. My VPN Reviews list all the major play in the personal VPN service industry , feel free to check around, read real customer VPN reviews and find out the best one for you