Horde_Mime_Part::isAttachment PHP Method

    public function isAttachment()
    {
        $type = $this->getType();
        switch ($type) {
            case 'application/ms-tnef':
            case 'application/pgp-keys':
            case 'application/vnd.ms-tnef':
                return false;
        }
        if ($this->parent) {
            switch ($this->parent->getType()) {
                case 'multipart/encrypted':
                    switch ($type) {
                        case 'application/octet-stream':
                            return false;
                    }
                    break;
                case 'multipart/signed':
                    switch ($type) {
                        case 'application/pgp-signature':
                        case 'application/pkcs7-signature':
                        case 'application/x-pkcs7-signature':
                            return false;
                    }
                    break;
            }
        }
        switch ($this->getDisposition()) {
            case 'attachment':
                return true;
        }
        switch ($this->getPrimaryType()) {
            case 'application':
                if (strlen($this->getName())) {
                    return true;
                }
                break;
            case 'audio':
            case 'video':
                return true;
            case 'multipart':
                return false;
        }
        return false;
    }