Handling input from script piped to netcat

I have a system that handles incoming emails to send them to a blackbox application at my job. The high level script is maintained by inittab to always run and runs a child script to do the actual work with this command:

$SCRIPT | nc -l -p $PORT

The script itself reads from a named pipe, does a bit of parsing and processing of the data before calling echo to shuffle the data back through netcat to the process connected on $PORT.

What I need is some method to handle incoming data from the far end of my pipe. When I make a request within the application to close the connection it sends back a string (I can define it to whatever I want) and waits for my script to close the pipe. I currently am struggling to understand how I can add in the functionality to read incoming data from the other end; verify it is the command to close the pipe, and then exit the script.

My script (in a nutshell) looks like this:

while true ; do
  email_input="`cat "$pipe"`"
  if [[ $email_input =~ .*escape_queue.* ]] ; then
    break;
  fi
  echo "`parse`"
done

I'm open to the possibility of having to alter the program flow, I just can't wrap my head around how I would be able to read the data incoming asynchronously since the script blocks on cat $pipe until a new email is received to process.

If its not clear, I'm at a novice level with bash scripting and am always open to suggestions for improvement.

UPDATE I've changed my script call to

$SCRIPT | nc -l -p $PORT > $nc_data

and within the script itself

netcat_response="`cat "$nc_data"`";
if [[ "$netcat_response" =~ "exit" ]] ; then
  cat /dev/null > $nc_data
  break;
fi

At this point the script terminates once a new message is piped into the fifo. This means that I will always lose 1 message as it gets read by the script and then the script terminates. The script still blocks on the cat until something is read. Worst case scenario this will have to do.