Added a section documenting the script

check-postfix.sh

@@ -1,5 +1,33 @@
 #!/usr/bin/bash
 
+
+#############################################################################################################
+# check-postfix.sh                                                                                          #
+#############################################################################################################
+#                                                                                                           #
+#  This script is just something I cooked up for work. I setup a server with posftix configured as an`      #
+#  email/smtp relay so that some of our old equipment can still function without having to try and          #
+#  configure our commercial Email Server to accept unauthed requests to send email.                         #
+#                                                                                                           #
+#  This requres a few packages to be installed:                                                             #
+#  - postfix (of course)                                                                                    #
+#  - telnet                                                                                                 #
+#  - sendmail                                                                                               #
+#                                                                                                           #
+#  The issue is if the postfix service dies and fails to come back up after a restart via this script,      #
+#  you will be unable to send any emails via a smtp client (as they will try to contact the service         #
+#  on the server itself). So the only workaround I was able to find is to manually send the email via       #
+#  telnet using a coproc. You could use a smtp library with python or perl, but I like to keep these        #
+#  scripts using a single language wherever possible.                                                       #
+#                                                                                                           #
+#  Since telnet is just a basic tcp client we are able to interact with the smpt port on a mailserver       #
+#  (port 25). So setting it up as coproc allows us to run a concurrent process and pipe commands into       #
+#  the file-descriptor to send the commands to the mailserver. Which allows us to manually send an email    #
+#  to an authoritative email server (provided they don't have your IP blocklisted or are filtering          #
+#  traffic on port 25).                                                                                     #
+#                                                                                                           #
+#############################################################################################################
+
 # BEGIN: Variables
 ## Duration to wait to see if service has come back up
 DURATION=10