Is Gmail asocial network?
Gmail is not a social network but is a Mailing system. Google+ is a social network of Google. You can view other's profile on social network.
If Gmail is blocked, there is no way of getting on to it on that internet connection. Try connecting to another network. Or you could ask the owner of the network to unlock it. There is no way to get on to Gmail on that internet connection beside hacking into the connection, which is not recommended. Sorry if i couldn't help you!
Gmail, Yahoo! Mail, Hotmail are great examples of portlet applications as companies such as Google have many different applications hosted under their network. Just as Gmail is a portlet application to Google's portal your online banking website is just a portlet application to the bank's financial infrastructure.