Spam attack/relay on Qmail
The attacker send an email to unexistentuser@localdomain.com usig forged headers as the email came from finaldestination@aol.com
Because the user does not exist the server will bounce back the message to finaldestination@aol.com.
With proper formatting the email will go very well on aol servers. I tested this method against several qmail servers and all are vulnerable.
Any suggestion or patch would be really appreciated.
