No, of course not. That's why Knowspam.net allows you to send mail through their system. Every recipient of an email you send is automatically placed on the whitelist and can mail you without ever seeing a challenging message.
To send mail through Knowspam.net:
- Set the outgoing (SMTP) server address in your email client to "knowspam.net".
- Make sure SMTP authentication is enabled.
- Use your Knowspam.net user name/passphrase combination for SMTP authentication, too.