Hmm. I think I'm in trouble if the support site itself is incapable of displaying accented characters properly.
Corrupted characters in a problem report about corrupted characters. Oh dear.
My analysis of the problem is that the content in the middle is contained within a frame, and is actually encoded in ISO-8859-1 - but doesn't have an encoding declaration. And the containing HTML page, of course, declares that it is UTF-8. So poor Mozilla gets very confused. And our poor users continue to get corrupted characters in their reminder and overdues notices.
Note: Some information removed from the screencap to protect the innocent - the client care people are actually excellent folk, and I'm sure they're just as frustrated by the problem reporting system as we are.