Open the letter - add a Createdate field at the end with the following
switch

{CREATEDATE \@ "d MMM yyyy HH.mm}

This will give you the time and date you created the document. Make a note
of it and close the document without saving it.

Tue, 31 Jan 2006 09:05:19 +0000 from  <dboysen@myway.com>:

Find the letter file in Explorer, and right-click on it. Select
Properties. That will show you date and time created. (If you can't
find it in Explorer, try Search with a phrase that's in the letter,
and that might find it.)

However, nothing you can get off your computer is what I would call
proof for a court case -- the best it can do is refresh your memory.
In other words, it can help you avoid making an honset mistake but it
can't rule out a deliberate lie. For instance, you could very well
have changed your computer's date and time five minutes ago, created
the letter, then changed the computer date/time back, if you were
trying to create a false trail.

Understand I'm not saying you _did_ do this or _would_ do this, just
that it's possible. And since it's possible, it means that the date
and time on a file don't prove anything in a legal sense.

Someone else suggested the CREATEDATE field within Word. This has all
the above disadvantages, _plus_ you actually have to alter the file.