enable "no authentication" for a SMTP server

[King Coffee]

Hello,

I'm running the a system.net smtp mail application.
The SMTP server do not require authentication.

In a web.config app in which I do use authentication,
I have network Credentials set to false. A weird connotation.

However, how can enable "no authentication" for a SMTP mail
server in the web.config file?

Thanks for your help.

Sincerely,
King