Zend_Mail::clearHeader PHP Method

    public function clearHeader($headerName)
    {
        if (isset($this->_headers[$headerName])) {
            unset($this->_headers[$headerName]);
        }
        return $this;
    }

 /**
  * @group ZF-10367
  */
 public function testClearHeader()
 {
     $mail = new Zend_Mail();
     $mail->addHeader('foo', 'bar');
     $headers = $mail->getHeaders();
     $this->assertTrue(isset($headers['foo']));
     $mail->clearHeader('foo');
     $headers = $mail->getHeaders();
     $this->assertFalse(isset($headers['foo']));
 }