Wraps words on a single line.
Callback for array_walk() winthin drupal_wrap_mail().
function _drupal_wrap_mail_line(&$line, $key, $values) {
// Use soft-breaks only for purely quoted or unindented text.
$line = wordwrap($line, 77 - $values['length'], $values['soft'] ? " \n" : "\n");
// Break really long words at the maximum width allowed.
$line = wordwrap($line, 996 - $values['length'], $values['soft'] ? " \n" : "\n", TRUE);
}