$path =  storage_path('app/letters/letter.pdf');
 $post = 'file=@' . $path;
 curl_setopt($ch, CURLOPT_URL, 'https://sign.zoho.com/api/v1/requests');
 $authorization = 'Authorization: Zoho-oauthtoken ' . $token;
 curl_setopt($ch, CURLOPT_HTTPHEADER, [$authorization]);
 curl_setopt($ch, CURLOPT_HEADER, 0);
 curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
 curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
 $entriesData = ['data' => [
     'requests' => [
         'request_name' => "NDA ",
         'actions' => [
             'recipient_name' => 'test',
             'recipient_email' => $mail,
             'action_type' => 'sign',
             'verify_recipient' => false,
         ],
         'is_sequential' => false,
     ]
 ]];
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($entriesData));
 $output = curl_exec($ch);