https://mail.google.com/intl/en/mail/help/about.html

gmail.com redirects you to mail.google.com/mail which will redirect you to /?ServiceLogin

    curl -v gmail.com
    * Adding handle: conn: 0x7fa939804000
    * Adding handle: send: 0
    * Adding handle: recv: 0
    * Curl_addHandleToPipeline: length: 1
    * - Conn 0 (0x7fa939804000) send_pipe: 1, recv_pipe: 0
    * About to connect() to gmail.com port 80 (#0)
    *   Trying 74.125.225.86...
    * Connected to gmail.com (74.125.225.86) port 80 (#0)
     GET / HTTP/1.1
    > User-Agent: curl/7.30.0
    > Host: gmail.com
    > Accept: */*
    > 
    < HTTP/1.1 301 Moved Permanently
    < Location: http://mail.google.com/mail/