When you install the Pushmail client on your mobile phone, every time there is a new email in your mailbox, the email platform will send 1 short message with special format to your mobile phone (the number is 10655462), and the Pushmail client will receive the short message in the background (there will be no short message in the SMS inbox), and then open the GPRS network to connect to the email platform to receive the email. SMS is free, which can trigger the mobile phone Pushmail client to receive new emails.