Attacks

["icakmakli"<icakmakli @ ykb . com>]

Hi,
I know that'a silly question.
May someone make an smtp connection with changing its source address?
Someone makes an smtp connection to a firewall with a source address xxxxxx
and makes mail bombing with more than 100.000 mails. I blacklist the IP
address. But still it attempts to connect to the firewall. Thanks.