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Automated Emails with Supabase Database Triggers

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The Problem It Solves

• Setting up a queue system like BullMQ, Celery, or AWS SQS.
• Running separate worker processes or Docker containers.
• Deploying serverless Edge Functions and managing webhooks.
• Handling connection retries and dead-letter queues.

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How Mailofly Helps

• Zero infrastructure: Dispatches emails straight from PostgreSQL using the native pg_net extension.
• Instant, sub-second delivery: Triggers fire the millisecond your database transaction commits.
• Non-blocking execution: Uses asynchronous HTTP requests so your database queries and application response times are never slowed down.
• Automatic column mapping: All row columns (name, plan, amount, etc.) are automatically passed into your template’s merge variables.
• Built-in HMAC security: Payloads are cryptographically signed using pgcrypto to prevent tampering.

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How It Works

1. Application Event: A user interacts with your app, triggering an INSERT or UPDATE into your Supabase database table.
2. PostgreSQL Trigger: An AFTER INSERT OR UPDATE trigger installed by Mailofly packages the row data into JSON.
3. Async HTTP Request: The pg_net extension sends an asynchronous HTTP POST request to Mailofly’s webhook endpoint.
4. Signature Verification & Rendering: Mailofly validates the HMAC-SHA256 signature, extracts the recipient’s email address from your designated column, populates template variables ({{name}}, {{plan}}), and delivers the message.

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Step-by-Step Tutorial

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Step 1: Create Your Supabase Table

CREATE TABLE public.subscribers (
  id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
  name text NOT NULL,
  email text NOT NULL,
  plan text NOT NULL DEFAULT 'Free',
  created_at timestamptz DEFAULT now()
);

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Step 2: Prepare Your Email Template in Mailofly

1. In the Mailofly dashboard, go to Templates and click Create Template.
2. Give your template a name (e.g. Welcome Subscriber).
3. Add subject line: Welcome to our platform, {{name}}!
4. Write your HTML content using merge tags that correspond to your table’s columns:

<div style="font-family: sans-serif; max-width: 600px; margin: 0 auto;">
  <h2>Welcome to the team, {{name}}! 👋</h2>
  <p>Thank you for subscribing to our <strong>{{plan}}</strong> plan.</p>
  <p>We're thrilled to have you on board. If you have any questions, simply reply directly to this email.</p>
  <br />
  <p>Cheers,<br />The Mailofly Team</p>
</div>

5. Click Save Template.

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Step 3: Connect Supabase in Mailofly

1. In Mailofly, navigate to Integrations.
2. Select the Supabase card.
3. Click Connect with Supabase.
4. In the Supabase OAuth authorization window, select your organization and project, then click Authorize.

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Step 4: Create the Database Trigger

1. In the Supabase integration view in Mailofly, click Add Trigger.
2. Configure the trigger parameters:
   • Project: Select your connected Supabase project.
   • Table: Select public.subscribers.
   • Event: Choose INSERT (to fire on new signups) or UPDATE (for status updates).
   • Recipient Column: Select email.
   • Email Template: Select the Welcome Subscriber template you created in Step 2.
3. Click Create Trigger.

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Step 5: Test the Integration

INSERT INTO public.subscribers (name, email, plan)
VALUES ('Alex Rivers', 'you@example.com', 'Enterprise Pro');

1. Check you@example.com—your personalized welcome email will arrive with Alex Rivers and Enterprise Pro populated.
2. In Mailofly, view the Integrations page to see the trigger’s Emails sent count increment.
3. Inspect detailed delivery status, open rates, and click tracking in the Logs tab.

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Verifying in PostgreSQL

SELECT id, status_code, url, error_msg, created
FROM net._http_response
ORDER BY id DESC
LIMIT 5;

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Pro Tips & Best Practices

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Next Steps

• Supabase Integration Reference — Technical specifications, cryptographic signing details, and extension requirements.
• Template Variables & Personalization — Learn about formatting dates, fallback values, and conditionals.
• Custom Domains Setup — Connect your own sending domain for maximum inbox deliverability.