Yes, as @JMichaelTX has said, the script is for Apple’s Mail program. Outlook’s AppleScript dictionary might be similar to the one of Apple Mail up to a certain degree, but there are certainly terms that differ.
You can look up Outlook’s dictionary by doing this:
- Open the Script Editor program (/Applications/Utilities/Script Editor.app)
- In the File menu of Script Editor go to Open Dictionary
- Select Outlook from the list
Now you can see the contents of Outlook’s dictionary. If it’s not too different you may be able to adapt the script. I don’t have Outlook installed on any computer, so I can’t help you here.
Also, in the very intro to the code you mention "use scripting additions" - can you advise what you mean?
This is not a mention, this is part of the code. It allows the script to use external libraries (“scripting additions”).