How automatic do you want it to be? You could write a VBA program that sends an email, and save it within each document so as to run automatically whenever you save it. But that doesn't sound very satisfactory to me; you'd have to trust that you'll never want to save it without notifying everyone, and then too you have to have a copy in every Office document in the folder (or at least every document for which you want notification).

Or you could write the same program in VBScript; it wouldn't run automatically, but you could send a standard email just by double clicking on the icon after saving one of the documents. But it wouldn't name which document(s) had changed unless you wanted to type in the document names each time; that doesn't sound like a great solution either.

Are they all Excel documents? I think it's possible to write a VBA program that resides not in any one workbook but in a sort of central workbook that is open whenever you're using Excel; maybe you could get it to notice when you save one of the documents in that folder and send the email. Then it'd happen automatically and exist in just one place. But it still would send it every time you save one of those documents, which may not suit you. (It certainly wouldn't suit me.)