I just reread again the faq and saw that giving a SG address as forwarding address is forbidden for obvious looping reasons.
This is a question to evaluate SG security. It could be imagine that
badspammer could set up an SG account. suscribe to millions sites with the given address. Accept suscriptions in the given email address. Then, make forward that email address to the SG address, but before, make the initial a trusted sender of the account. Then, wait for SG to blow.
Has this scenario been though? Is it possible to set up as a trusted or exclusive sender one of the previous forwarding addresses? If it is forbidden, what about another forwarding loop to make the attack?
Thanks,
CTone