Hi all,
There is a guy sending spam messages to a domain serverd on my box
from his adsl connection.The mails are being sent as they are coming from xxx@microsoft.com that's why I can not just put a record to badmailfrom as I cant block microsoft.com really.What I need to do is to block his ip address and hostname of his adsl connection or simply drop them without generating bounce messages. Any help will be appreciated.

Why not just block the IP at your firewall?

Thanks for the reply.
Do you know if it is possible to block an ip from a port only?
I am using kiss frewall.

Yes, it is possible to block based on a combination of IP and port. I don't have any experience with Kiss, but it shouldn't be difficult to figure out if you poke around a bit.