My SquirrelMail 1.4.0 installation has always worked fine, except for when sending a message containing one or more characters that have diacritical marks. I receive all mail fine, but when replying to something with French words in it, when I hit send I get back an error page that says "Not Acceptable. An appropriate representation of the requested resource /webmail/src/compose.php could not be found on this server."
The characters all look fine in the received email and look fine while composing the reply, but the reply always returns that error until I remove all characters with diacritical marks from body and subject. In SquirrelMail's config.php it has:
default_charset = 'iso-8859-1'
so I don't know what else to look at. I've used other SquirrelMail installations that work fine with French. Anyone have a clue as to what I've misconfigured?