It isn't *really* ISO8859-1; we hope it'll be UTF-8. But it doesn't make any
difference to the XML parsing, which is all ASCII anyway. It only affects
the *content* of the data nodes... and in fact it doesn't matter for those
*either* because libxml doesn't attempt to do any translation; it just gives
us the strings.

The *only* difference that setting ISO8859-1 makes, as far as I know, is that
it stops libxml from aborting when it sees legacy 8-bit crap in the content.
Which *does* happen with broken mails, especially spam.