Dear Experts:

I need help with a macro:

As soon as a user enters a certain string, say "text" in any row of
Column A (with the exception of the column heading) , a msgbox is to
pop up, saying "This is not allowed!"

I would favour a macro solution, but if there is a built-in
functionality to perform this, that would be great too.

Help is much appreciated. Thank you very much in advance.

Regards, Andreas