I have configured my outlook express setting in my pc for using g mail in it. but?

I want to send and receive my g mail accounts mail in outlook express, I have configured the settings those I got to know from internet only, I have got my gmail accounts all mail in outlook but cant send mail from this,,,,pls help,,,, follwing is the error I am getting





The message could not be sent because the server rejected the sender's e-mail address. The sender's e-mail address was 'example@gmail.com'. Subject 'Read: document', Account: 'imap.gmail.com', Server: 'smtp.gmail.com', Protocol: SMTP, Server Response: '530 5.7.0 Must issue a STARTTLS command first. b4sm7347874tic.22', Port: 25, Secure(SSL): No, Server Error: 530, Error Number: 0x800CCC78
I have configured my outlook express setting in my pc for using g mail in it. but?
http://www.howtoadvice.com/BlockedSMTP