To write a script to accept a message in the "arrive action", it is best to proceed as follows:

Read the chapter on the script API in this manual carefully.

You create a first draft of the script.

You press the validate button. This performs a syntax check. Any errors that occur are displayed in a message window. You correct these errors.

You press the save button to save the script. This activates the script immediately and processes messages in the way you have just programmed.

If you make major changes to a script, it is advisable to set up a test message box. In this message box, you can first check the incoming messages. If the script then works as desired, you can transfer the script to another message box.