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Each sms message you send will have a message id and attachment id with it.

There is an RC API that retrieve the message content in plain text:

/restapi/v1.0/account/~/extension/~/message-store/<message id>/content/<attachment id>

You can use this API in your code

Hi,

In order to receive incoming SMS, you need to subscribe a push notification for SMS, then use either Webhook or PubNub to receive the notification. When a notification of an incoming SMS message arrives, you can parse the payload to extract the body of the message.

I don't really understand your other question "get plain text of message body in mail instead of url of txt file" so please explain.

Some example codes:

// Subscribe for notification

function createSubscription() {

  var _eventFilters = [];  

  _eventFilters.push('/restapi/v1.0/account/~/extension/~/message-store/instant?type=SMS');

  return platform.post('/subscription',    {

    eventFilters: _eventFilters,       

    deliveryMode: {

      transportType: "WebHook",

      address: "Your_Webhook_Delivery_Address"

      }

  })

  .then(function(subscriptionResponse) {})

  .catch(function(e) { throw e; });

}

// receive notification via webhook and parse the response

app.post('/webhooks', function (req, res) {

  req.on('data', function(chunk) {

    body.push(chunk);

  }).on('end', function() {

    body = Buffer.concat(body).toString();

    var jsonObj = JSON.parse(body)   

    var senderNumber = jsonObj['body']['from']['phoneNumber']

    var text = jsonObj['body']['subject']

    ...

  });

})

For full demo please download this example

Hope this helps!
Phong