Zend Mail 1.12 lose line break

Question

when I try to get content from and email sent by yahoo.com with zend mail . Mail sent:

hello.
yeah1
yeah2
YAHOO!

reveiced from zend mail:

hello.=20 
yeah1yeah2YAHOO!=20

using this code

foreach (new RecursiveIteratorIterator($message) as $numPart => $part) {
    $content = Zend_Mime_Decode::decodeQuotedPrintable($part->getContent());
    echo "<textarea style='height: 400px;'>".($content)."</textarea>";
}

I don't understand why it losing line break. Working fine with gmail / outlook