In the case of programs like uucp, which must have world- writable home directories for the software to work properly, create a directory called .forward. Protect it by creating at least one dummy file in it, changing owner of the directory and file to root and set the permissions of both to 000. Route mail for uucp to a real user via an alias. Monitor your system logs regularly, frequently and carefully. Consider using procmail for your local delivery agent.
Many people believe it is the most secure local delivery agent.
Smap also makes attacks mounted by direct user telnet to port 25 difficult. You do not need to turn off all debugging, just SMTP debugging. To make sure it is off, telnet to port 25 and invoke the debug command. Make sure logging is enabled by setting the L option to nonzero. Many abnormal situations, like the example above, will be recorded.