Stu wrote:

Jlong wrote:
"Is this still the case when the original recipient of the letter still owns it?"

The Tolkien Estate owns the rights to anything he wrote, regardless of who possesses the letter.

I'm not sure how enforceable this would be, realistically. People publicly disclose the contents of letters written to them all the time (in legal disputes, for example), and they are not opening themselves up to legal proceedings by doing so. That said, the legal system favours the rich, so I have no doubt that the Tolkien Estate get their own way in most matters.