What are some ways to prevent spammers/exploits
Hello,I have had someone hack into a server of mine and send out an ebay password harvesting schema. I have no idea how he got in. I have been keeping all services patched and up to date, but somehow the guy still is able to send out spam. I have one IP address that he has used to exploit the server, have contacted ebay and done everything I know how to prevent this from happening.
It has gotten soo bad that rackshack has turned me off, and now godaddy has locked out my main business domain name. I hope I am not going to go out of business for this

Is there a way to stop mail from going out as the default server user through sendmail?
He used a form of form2mail to send this out, and I have somewhat of a trail that he left on the server through various logs and applications.