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📮

Postmark

Communications

Transactional email delivery with guaranteed speed

Postmark is the fastest transactional email delivery service used by developers who need guaranteed inbox delivery for receipts, invites, and alerts.

Details

Auth Type
API Key (X-Postmark-Server-Token header)
Rate Limit
Unlimited (rate plans vary)
Pricing
$1.50 per 1,000 emails
Full Docs
Step 1: Save your provider key

This is NOT your Callio key. Enter the API key from the provider's dashboard (e.g. OpenAI/SendGrid).

API Key (X-Postmark-Server-Token header)

1. Go to https://account.postmarkapp.com/servers 2. Select your server and click API Tokens 3. Copy the Server API Token

Get API Credentials

Getting Started

1

Try It Instantly

Click "Try It" above to test the API in the playground

2

Add to Your Agent

Click "Add to Agent" to get your API key and integrate

Common Use Cases

Password resets
Invoice delivery
Onboarding emails
Triggered alerts
Receipts

💻 Code Examples

Get started quickly with these code examples in your favorite language

curl -X GET \
  'https://www.callio.dev/api/proxy/postmark-email/endpoint' \
  -H 'Authorization: Bearer YOUR_CALLIO_KEY' \
  -H 'Content-Type: application/json'

💡 Tip: Replace YOUR_CALLIO_KEY with your actual Callio API key from the dashboard.

Ready to integrate Postmark?

Test endpoints live or generate your API key and start building in minutes

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