Instead , the challenge can be placed in the Bounce message when the receiving mail system gives a rejection - code during the SMTP session .
Problems with sending challenges to forged e-mail addresses can be greatly reduced by not creating a new message that contains the challenge .
The challenge can be placed in the Bounce message when the receiving mail system gives a rejection - code during the SMTP session .
Problems with sending challenges to forged e-mail addresses can be greatly reduced by not creating a new message that contains the challenge .