I've added the following sentence to the documentation of vm-in-reply-to-format:
If the format includes elements with non-ASCII characters, then "In-Reply-To" should be added to `vm-mime-encode-headers-regexp'.
I've added the following sentence to the documentation of vm-in-reply- to-format:
If the format includes elements with non-ASCII characters, then "In-Reply-To" should be added to `vm-mime- encode- headers- regexp' .