in order for the gmail SMTP server to relay the email message, the from address must be the same gmail address used in in the authentication settings.
the gmail server will not relay the email message if you use a different email address as the from address.
if you go to the advanced from options, you can use the dynamic binding as the Replay to address, so the SMTP Server sees the from address as being a valid email address, but when the receipt replies to the email, it uses the address from the form.
