Send An Email Via Google Apps Without An Ssl Cert?

I'm trying to send email via google apps from my asp.net app and am getting the following exception:

{"The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at "}

My Web.config has the following values:

<system.net>
<mailSettings>
<smtp from="user@domain.com"
deliveryMethod="Network">
<network host="smtp.gmail.com"
port="587"
userName="user@domain.com"
password="password"
enableSsl="true"/>
</smtp>
</mailSettings>