I had some problems with the german umlauts from a gmail fetched text. I lost an hour trying to find a solution. 

Hopefully this helps someone in need :)

<?php
$text = trim( utf8_encode( quoted_printable_decode(
                        imap_fetchbody( $this->inbox, $emailNo, $section ) ) ) );

$section was previously defined:
$section = empty( $attachments ) ? 1 : 1.1;
?>