Receiving emails

MailBlastr supports receiving email (commonly called *inbound*) alongside sending. Inbound is useful for building support inboxes, processing forwarded receipts and attachments, and replying to customers in-thread — all driven by your own code.

MailBlastr accepts every incoming message for your receiving domain, parses the body and attachments, stores the message, and then sends a POST request to a webhook endpoint you choose. Your application reacts to that callback.

How it works

MailBlastr processes all incoming mail for your receiving domain, parses the contents and attachments, and delivers an email.received webhook to your endpoint. You can either use a MailBlastr-managed domain or set up a custom receiving domain.

1. Get your receiving domain

Any email sent to an <anything>@<id>.mailblastr.app address is received by MailBlastr and forwarded to your webhook. To find your MailBlastr-managed receiving address:

1. 1
   Open Emails

   Go to the Emails page in the MailBlastr dashboard.

2. 2
   Select the Receiving tab

   Switch to the "Receiving" tab to see inbound configuration.

3. 3
   Copy your receiving address

   Open the row menu and choose "Receiving address" to copy your .mailblastr.app address.

2. Configure a webhook

Create a webhook endpoint that subscribes to the email.received event:

1. 1
   Open Webhooks

   Go to the Webhooks page in the dashboard.

2. 2
   Add a webhook

   Click "Add Webhook" and enter the public URL of your endpoint.

3. 3
   Subscribe to email.received

   Select the email.received event type and save.

3. Receive email events

In your application, create a route that accepts POST requests and reacts when the event type is email.received:

// app/api/events/route.ts (Next.js route handler)
import type { NextRequest } from 'next/server';
import { NextResponse } from 'next/server';

export const POST = async (request: NextRequest) => {
  const event = await request.json();

  if (event.type === 'email.received') {
    // event.data.email_id, event.data.from, event.data.to, ...
    return NextResponse.json(event);
  }

  return NextResponse.json({});
};

Once you receive the event you can fetch the full message and process its body and attachments. We strongly recommend verifying the webhook signature so only genuine MailBlastr requests are accepted.

The email.received payload

The webhook body carries the event envelope plus a data object with the message metadata — id, addressing, message_id, subject, and attachment metadata:

{
  "type": "email.received",
  "created_at": "2026-02-22T23:41:12.126Z",
  "data": {
    "email_id": "56761188-7520-42d8-8898-ff6fc54ce618",
    "created_at": "2026-02-22T23:41:11.894719+00:00",
    "from": "onboarding@mailblastr.dev",
    "to": ["delivered@mailblastr.dev"],
    "bcc": [],
    "cc": [],
    "received_for": ["forwarded@example.com"],
    "message_id": "<111-222-333@email.example.com>",
    "subject": "Sending this example",
    "attachments": [
      {
        "id": "2a0c9ce0-3112-4728-976e-47ddcd16a318",
        "filename": "avatar.png",
        "content_type": "image/png",
        "content_disposition": "inline",
        "content_id": "img001"
      }
    ]
  }
}

Envelope fields

The top-level envelope wraps every webhook and identifies the event:

data fields

The data object carries the parsed addressing and threading metadata for the received message:

What you can do with a received email

• Get the email content — HTML, plain text, and headers.
• Process attachments — download and inspect attached files.
• Forward the email to another address.
• Reply in the same thread using the original message_id.

FAQ

Will I receive mail for any address at my domain?

Yes. Once the MX record is in place for your custom domain, MailBlastr receives mail for *any* address at that domain — <anything>@yourdomain.tld. Filter or route on the to field of the event. The same applies to a MailBlastr-managed domain such as inbox.mailblastr.app.

Can I receive on a subdomain?

Yes. Add the MX record to any subdomain (e.g. subdomain.yourdomain.tld) and receive mail there.

Will I lose mail if my webhook endpoint is down?

No. MailBlastr stores every inbound message as soon as it arrives, so you can always retrieve it from the dashboard or via the Receiving API even if your endpoint was unavailable. Failed webhook deliveries are retried, and you can replay individual events from the Webhooks page.

How do I confirm a webhook really came from MailBlastr?

Every webhook is signed. Verify the signature headers before trusting the payload — see Verify webhook requests.