I posted a problem with sending email via smtp using Dot Net 2.0

I was told to look at adding authentication to my web.config file;  I added
the following:

authenticationMode="SSL"

I put this in my web.config mail settings and when I put the mouse
over it, i get the following message:

"The authenticationMode attribute is not declared"

Can you please help?

The entire web.config system.net.......

<system.net>

<mailSettings>

<smtp from="abc@gmail.com">

<network host="smtp.gmail.com" port="587" password="secret" userName="abc"
authenticationMode="SSL"/>

</smtp>

</mailSettings>

</system.net>