src/Message.php
public function withoutHeader($name)
    {
        if (isset($this->_headers[$name]))
        {
            unset($this->_headers[$name]);
        }

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

        return $this;
    }
{@inheritdoc}