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Notification inbox

How it works

Unlike other messages, inbox messages don’t necessarily appear immediately to users, and they don’t disappear when the user dismisses them. Instead, you’ll display these messages through a notification inbox that your audience can access at their leisure.

Customer.io delivers inbox messages as JSON payloads, not fully-rendered messages. The SDK helps you listen for these payloads, but you’ll determine how to display them in your own inbox client.

You can send an inbox message as a part of a campaign, broadcast, or transactional message.

Get the inbox instance

You’ll access inbox functionality through the inbox property on the in-app messaging module.

final inbox = CustomerIO.inAppMessaging.inbox;

Inbox methods

The inbox instance provides several methods to manage messages.

Inbox message payloads

Inbox messages are delivered as a JSON payload. The SDK helps you listen for the payload, but you’ll render the content in your own inbox client.

The client payload includes the following fields, but you’re most concerned with the properties object, which represents your message content. By default, we’ll send a title and body field, but you can add other fields like an image or a link—whatever you set up your inbox to expect.

Make sure that your team members know what payloads to send—especially if you expect different payloads for different topics or types of messages.

{
    "messageId": "1234567890",
    "sentAt": "2026-02-05T12:00:00Z",
    "expiresAt": "2026-02-05T12:00:00Z",
    "opened": false,
    "topics": ["orders", "shipping"],
    "type": "order_shipped",
    "properties": {
        "title": "Hey Cool Person, your order shipped!",
        "body": "You can track your order #1234567890 here:",
        "link": "https://example.com/orders/1234567890"
    }
}

Inbox topics and types

When you send an inbox message, you can assign it to one or more topics. You can use these topics to filter messages when you fetch them. You can also use the topics to determine how to render the messages in your notification inbox.

Messages also have a type. Think of this like a sub-category or topic for a message. For example, you might have orders and sale topics, where orders don’t have images but sale topics might. Or, within the orders topic, you might have order_placed and order_shipped types, where order_placed lists order details and images of purchased products and order_shipped provides a link to the tracking information for the order that opens in a new tab.

Setup your notification inbox

Inbox messages are just JSON payloads. You’ll need to build your own inbox client to display the messages. The code below gives you a starting point, but you can build your own inbox client however you want.

Fetch messages

// Fetch all messages
final messages = await inbox.fetchMessages();

// Fetch messages filtered by topic
final promotions = await inbox.fetchMessages(topic: 'promotions');

Stream messages for real-time updates

// Stream all messages (real-time updates)
inbox.messages().listen((messages) {
  // Update your UI with the messages
  updateInboxUI(messages);
});

// Stream messages filtered by topic
inbox.messages(topic: 'promotions').listen((messages) {
  // Update your UI with promotions
  updatePromotionsUI(messages);
});

Mark messages as opened or unopened

// Mark a message as opened
inbox.markMessageOpened(message);

// Mark a message as unopened
inbox.markMessageUnopened(message);

Track message clicks

// Track a click without an action name
inbox.trackMessageClicked(message);

// Track a click with an action name
inbox.trackMessageClicked(message, actionName: 'view_details');

Delete messages

// Mark a message as deleted
inbox.markMessageDeleted(message);

Working with message properties

You can access message properties to display custom content in your inbox:

// Access message properties
final title = message.properties['title'] as String?;
final body = message.properties['body'] as String?;
final link = message.properties['link'] as String?;
final imageUrl = message.properties['image'] as String?;

// Handle message action when user taps
void handleMessageTap(InboxMessage message) {
  // Mark as opened
  inbox.markMessageOpened(message);

  // Track the click
  inbox.trackMessageClicked(message);

  // Open link if available
  final link = message.properties['link'] as String?;
  if (link != null) {
    launchUrl(Uri.parse(link));
  }
}