Transactional API

Common Use Cases

- Password Reset
- Order Confirmation
- Welcome Email
- Account Deletion
- Purchase Receipt
- Shipping Notifications
- Account Verification
- Payment Confirmations

Key Features

Automatic Contact Management

Contact Upsert: Contacts are automatically created or updated before sending
Profile Enrichment: Template data is automatically merged with existing contact profile information
Data Consistency: Ensures contact information is always current

Template Data Enrichment

When you send a transactional email, Notifuse automatically:

Looks up the contact by email address in your workspace
Merges your API data with the existing contact profile
Enriches the template with the complete contact information
Sends the personalized email with all available data

Example: If your API sends {"order_id": "12345"} but the contact profile contains {"first_name": "John", "last_name": "Doe"}, the template will have access to both the order data and the contact’s full profile.

Deduplication with External ID

Prevent Duplicates: Use external_id to prevent sending the same notification multiple times
Idempotent Requests: Notifications with the same external_id will only be sent once
Custom Identifiers: Use your own unique identifiers (order IDs, event IDs, etc.)

Example: Setting external_id: "order-12345" ensures that even if your system sends the same order confirmation multiple times, the email will only be delivered once.

Email Delivery Options

Configure email routing with flexible options:

From Name: Override the default sender display name
Subject: Override the template subject line (supports Liquid templating)
Reply-To: Set custom reply-to addresses
CC: Add carbon copy recipients
BCC: Include blind carbon copy recipients
Attachments: Attach files to emails (PDFs, images, documents, etc.)

API Endpoint

Send transactional emails using a simple POST request:

Request

curl -X POST \
  "https://v3.notifuse.com/api/transactional.send" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
  "workspace_id": "your_workspace",
  "notification": {
    "id": "password_reset",
    "external_id": "pwd-reset-user123-20240101",
    "channels": ["email"],
    "contact": {
      "email": "user@example.com"
    },
    "data": {
      "reset_token": "abc123",
      "expiry_time": "2024-01-01T12:00:00Z"
    },
    "metadata": {
      "user_id": "12345",
      "trigger": "forgot_password",
      "source": "web_app"
    },
    "email_options": {
      "from_name": "Support Team",
      "subject": "Reset your password, {{ contact.first_name }}",
      "reply_to": "support@yourcompany.com",
      "cc": ["admin@yourcompany.com"],
      "bcc": ["logs@yourcompany.com"],
      "attachments": [
        {
          "filename": "reset-guide.pdf",
          "content": "JVBERi0xLjQKJeLjz9MKMy4uLg==",
          "content_type": "application/pdf"
        }
      ]
    }
  }
}'

Parameters

Parameter	Type	Required	Description
`workspace_id`	string	Yes	Your workspace identifier
`notification.id`	string	Yes	Template identifier for the email
`notification.external_id`	string	No	Unique identifier for deduplication
`notification.channels`	array	Yes	Must include “email”
`notification.contact`	object	Yes	Contact object with at least an email field
`notification.data`	object	No	Template variables for email content
`notification.metadata`	object	No	Tracking data (not available in templates)
`notification.email_options`	object	No	Email routing configuration

Email Options

Parameter	Type	Description
`from_name`	string	Override default sender display name
`subject`	string	Override template subject line (supports Liquid templating, max 255)
`reply_to`	string	Set custom reply-to email address
`cc`	array	List of carbon copy recipients
`bcc`	array	List of blind carbon copy recipients
`attachments`	array	File attachments (max 20 files, 3MB per file, 10MB total)

Data vs Metadata

Template Variables (`data`)

The data object contains variables that will be available in your email templates:

{
  "data": {
    "order_id": "ORD-12345",
    "total": "$99.99",
    "discount_code": "WELCOME20"
  }
}

These can be used in templates as: {{ order_id }}, {{ total }}, {{ discount_code }}

Tracking Data (`metadata`)

The metadata object stores information for analytics and tracking but is not available in templates:

{
  "metadata": {
    "campaign_id": "welcome-series",
    "source": "mobile_app",
    "user_segment": "premium"
  }
}

Use metadata for internal tracking, analytics, and reporting purposes.

Email Attachments

Send files with your transactional emails such as invoices, receipts, tickets, or documents. Attachments are automatically deduplicated and stored efficiently.

Attachment Limits

Maximum files: 20 attachments per email
File size: 3MB per file
Total size: 10MB per email
Supported formats: All file types (PDF, PNG, JPEG, DOCX, etc.)

Attachment Parameters

Parameter	Type	Required	Description
`filename`	string	Yes	Name of the file (max 255 characters)
`content`	string	Yes	Base64-encoded file content
`content_type`	string	No	MIME type (e.g., “application/pdf”), auto-detected if not provided
`disposition`	string	No	”attachment” (default) or “inline”
`content_id`	string	No	Content-ID for inline attachments, referenced from the HTML body as `<img src="cid:...">`. Only allowed when `disposition` is “inline”. Defaults to the filename when omitted.

Example with PDF Invoice

{
  "workspace_id": "your_workspace",
  "notification": {
    "id": "order_confirmation",
    "contact": {
      "email": "customer@example.com"
    },
    "data": {
      "order_id": "ORD-12345",
      "total": "$99.99"
    },
    "email_options": {
      "attachments": [
        {
          "filename": "invoice-12345.pdf",
          "content": "JVBERi0xLjQKJeLjz9MKMy4uLg==",
          "content_type": "application/pdf",
          "disposition": "attachment"
        }
      ]
    }
  }
}

Example with Multiple Attachments

{
  "email_options": {
    "attachments": [
      {
        "filename": "invoice.pdf",
        "content": "JVBERi0xLjQKJeLjz9MK...",
        "content_type": "application/pdf"
      },
      {
        "filename": "receipt.png",
        "content": "iVBORw0KGgoAAAANSUhEU...",
        "content_type": "image/png"
      },
      {
        "filename": "terms.docx",
        "content": "UEsDBBQABgAIAAAAIQ...",
        "content_type": "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
      }
    ]
  }
}

Inline Images (Content-ID)

Embed per-recipient images — such as QR codes or personalized graphics — directly inside the email body instead of hosting them at a URL. Set disposition to "inline" and give the attachment a content_id, then reference it from your template’s HTML as <img src="cid:...">:

{
  "email_options": {
    "attachments": [
      {
        "filename": "check-in-qr.png",
        "content": "iVBORw0KGgoAAAANSUhEU...",
        "content_type": "image/png",
        "disposition": "inline",
        "content_id": "checkInQr"
      }
    ]
  }
}

And in the email template:

<img src="cid:checkInQr" alt="Your check-in QR code" />

Notes:

content_id may only contain letters, digits, and the characters . _ - @ (max 255 characters), and is only accepted when disposition is "inline".
When content_id is omitted, the filename is used as the Content-ID, so <img src="cid:check-in-qr.png"> also works.
Inline images are delivered inside a multipart/related MIME part alongside the HTML body, so email clients embed them rather than showing them as downloadable attachments.
Because the image travels inside the message body, it is never fetched or logged by link proxies or image-caching services — suitable for per-recipient secrets like QR codes.
On Mailgun, the content_id also becomes the delivered part’s filename, so prefer a content_id with a file extension (e.g. checkInQr.png) when sending through Mailgun.

Common Use Cases

Order Confirmations: Attach invoices and receipts
Booking Confirmations: Attach tickets and itineraries
Legal Documents: Attach contracts and agreements
Reports: Attach analytics reports and summaries
Certificates: Attach completion certificates and badges
Event Tickets: Embed per-recipient QR codes as inline images

SMTP Bridge

Notifuse includes a built-in SMTP bridge server that allows you to send transactional emails using standard SMTP clients instead of HTTP API calls. This is particularly useful when:

Legacy Systems: Integrating with existing applications that only support SMTP
Email Libraries: Using standard email libraries in any programming language
Framework Integration: Working with frameworks that have built-in SMTP support
Gradual Migration: Moving from existing email providers without changing application code

How It Works

The SMTP bridge server accepts emails via SMTP on port 587 (STARTTLS) or 465 (implicit TLS). The email body must contain a JSON payload matching the Transactional API format. Authentication is done using your workspace API credentials.

Sending Emails via SMTP

Authentication

Username: Your workspace API email (the email associated with your API key)
Password: Your workspace API key
Security: STARTTLS (port 587) or implicit TLS / SMTPS (port 465), depending on your SMTP_BRIDGE_TLS setting
Server: Your configured SMTP bridge host (e.g., smtp.yourdomain.com)

Email Format

The email body must be a JSON payload matching the Transactional API format:

{
  "workspace_id": "your_workspace",
  "notification": {
    "id": "password_reset",
    "external_id": "unique-id-123",
    "channels": ["email"],
    "contact": {
      "email": "user@example.com",
      "first_name": "John",
      "last_name": "Doe"
    },
    "data": {
      "reset_token": "abc123",
      "expiry_time": "1 hour"
    }
  }
}

Template Integration

Data Structure in Templates

Your templates have access to both API data and contact profile:

<!-- From API data -->
Hello! Your order #{{ order_id }} has been confirmed.

<!-- From contact profile (automatically enriched) -->
Dear {{ contact.first_name }} {{ contact.last_name }},

<!-- Combining both -->
We've sent your order #{{ order_id }} to {{ contact.email }}.

Complete Example

API Request:

{
  "workspace_id": "your_workspace",
  "notification": {
    "id": "order_confirmation",
    "external_id": "order-12345-confirmation",
    "contact": {
      "email": "sarah@example.com"
    },
    "data": {
      "order_id": "ORD-12345",
      "total": "$99.99",
      "items": ["Product A", "Product B"]
    },
    "metadata": {
      "campaign_id": "order-confirmations",
      "source": "checkout"
    }
  }
}

Existing Contact Profile:

{
  "first_name": "Sarah",
  "last_name": "Johnson",
  "email": "sarah@example.com",
  "phone": "+1234567890"
}

Available in Template:

Hi {{ contact.first_name }}!

Your order #{{ order_id }} totaling {{ total }} has been confirmed.

Items:
{% for item in items %}
- {{ item }}
{% endfor %}

We'll send updates to {{ contact.email }}.

API Reference

Deduplication Examples

Order Confirmations

{
  "external_id": "order-12345-confirmation"
}

Password Resets

{
  "external_id": "pwd-reset-user123-20240101"
}

Welcome Emails

{
  "external_id": "welcome-user123"
}

Using consistent external_id patterns ensures that duplicate notifications are automatically prevented, even if your application sends multiple requests. For complete API documentation and additional parameters, see the API Reference.

Getting Started

Features

Tutorials

Integrations

Email Providers

Common Use Cases

Key Features

Automatic Contact Management

Template Data Enrichment

Deduplication with External ID

Email Delivery Options

API Endpoint

Request

Parameters

Email Options

Data vs Metadata

Template Variables (`data`)

Tracking Data (`metadata`)

Email Attachments

Attachment Limits

Attachment Parameters

Example with PDF Invoice

Example with Multiple Attachments

Inline Images (Content-ID)

Common Use Cases

SMTP Bridge

How It Works

Sending Emails via SMTP

Authentication

Email Format

Template Integration

Data Structure in Templates

Complete Example

API Reference

Deduplication Examples

Order Confirmations

Password Resets

Welcome Emails

​Common Use Cases

​Key Features

​Automatic Contact Management

​Template Data Enrichment

​Deduplication with External ID

​Email Delivery Options

​API Endpoint

​Request

​Parameters

​Email Options

​Data vs Metadata

​Template Variables (data)

​Tracking Data (metadata)

​Email Attachments

​Attachment Limits

​Attachment Parameters

​Example with PDF Invoice

​Example with Multiple Attachments

​Inline Images (Content-ID)

​Common Use Cases

​SMTP Bridge

​How It Works

​Sending Emails via SMTP

​Authentication

​Email Format

​Template Integration

​Data Structure in Templates

​Complete Example

​API Reference

​Deduplication Examples

​Order Confirmations

​Password Resets

​Welcome Emails

Common Use Cases

Key Features

Automatic Contact Management

Template Data Enrichment

Deduplication with External ID

Email Delivery Options

API Endpoint

Request

Parameters

Email Options

Data vs Metadata

Template Variables (`data`)

Tracking Data (`metadata`)

Email Attachments

Attachment Limits

Attachment Parameters

Example with PDF Invoice

Example with Multiple Attachments

Inline Images (Content-ID)

Common Use Cases

SMTP Bridge

How It Works

Sending Emails via SMTP

Authentication

Email Format

Template Integration

Data Structure in Templates

Complete Example

API Reference

Deduplication Examples

Order Confirmations

Password Resets

Welcome Emails