Most operating systems come with security measures including e-mail scanners. These programs scan and filter mail for possibly unfriendly attachments. Hire a skilled system administrator. Your administrator should know your system well enough to anticipate when problems might arise. This person will use benchmarks to monitor performance and server logs to monitor trends in performance and traffic.
Patches are security updates that cover known holes in the security system.
Whoever runs the system should maintain a regular schedule of checking with the vendor for flaws, bugs, or patches that might have been reported. Remove unused communication ports. Communication ports are used to allow data to enter and leave the system. Each system will typically have more than 60,000 possible ports. You can use system administration tools to close any unused ports.