I ran into this today, I am definitely not a scripting guru by any means but I ran across a situation where I wanted to send a new email in response to a receipt of an email (I did not want to forward the content of the existing but a brand new email)

This turned out to be trickier than I thought there was no built in function so I had to make a script (something I have done with other office products)

Step 1

Create the script itself

I used the following source as my template, it is well documented no need for me to post it again there is one change you have to make to get outlook to be able to use it as a script in a rule though

http://www.planet-source-code.com/vb/scripts/ShowCode.asp?lngWId=4&txtCodeId=6480

The change is as follows (Taken from this KB http://support.microsoft.com/kb/306108)

You have to create the sub as an outlook mail item

Example:

Sub CustomMailMessageRule(Item As Outlook.MailItem)
This little trick was actually not the easiest to determine for a newb like me
At that point you should be able to have a working mail script to include in a rule
Step 2
You just have to attach it to a mail rule you do that by selecting ”run a script” and picking your script from the list provided (as long as you have declared the Sub right it should show in the list)
Use this rule only for good