Posting a message when opening a spreadsheet

Hello Forum,


Does anyone know a way to post a message or 'alert' which appears every time you open the spreadsheet?


For example: I will be posting a spreadsheet with a lot of data on it for a website and I would like a copyright/permission notice to appear anytime someone downloads/opens the spreadsheet. (I would like this to be something I could write obviously as opposed to a generic message)


If it was a 'popup' (something they had to close or move out of the way), that would be perfect.


Let me know if you have any ideas.


Thanks,
Andrew

edit: I would like to do this without using macros if possible.