Postmark API

Name: Postmark API API
Brand: Postmark API
Availability: InStock

★ Only Publicly Available OpenAPI DocumentCommunicationsEmail DeliveryapiKey43 EndpointsREST

For Agents

Send transactional emails, track bounces and delivery events, manage templates, and process inbound messages. Provides per-message open and click tracking with detailed statistics.

Quickstart

Get started with Postmark API in minutes using your preferred integration method.

# Add to your MCP client config (Claude Desktop, Cursor, Windsurf)
{
  "jentic": {
    "url": "https://api.jentic.com/mcp",
    "auth": "oauth"
  }
}

# Then ask your agent:
"send a transactional email with tracking"

# → Jentic returns the GET /events tool with parameter schema, agent executes.

Capabilities

What an agent can do with Postmark API API.

Send single emails, batch messages, or template-based emails with variable substitution

Track delivery statistics including opens, clicks, bounces, and spam complaints per message

Search and retrieve outbound message details with full header dumps

Process inbound emails with bypass and retry controls for failed messages

GET STARTED

Start building with Postmark API API

Explore with Jentic

View OpenAPI Document

Jentic publishes the only available OpenAPI document for Postmark API, keeping it validated and agent-ready.

The Postmark API handles transactional email delivery with 43 endpoints covering sending (single, batch, and templated), bounce management, inbound message processing, outbound message search, delivery statistics, and template management. It tracks opens, clicks, and spam complaints with per-message granularity and supports inbound email processing with bypass and retry controls. Authentication uses a per-server token in the X-Postmark-Server-Token header.

Use Cases

Patterns agents use Postmark API API for, with concrete tasks.

★ Transactional Email Delivery

Send order confirmations, password resets, and notification emails through Postmark's high-deliverability infrastructure. The API supports single sends, batch sends of up to 500 messages, and template-based sends with dynamic variable substitution. Each message receives a unique MessageID for tracking through delivery, open, and click events. Average delivery time is under 10 seconds for transactional messages.

Send a templated email using POST /email/withTemplate with template alias 'order-confirmation', recipient 'user@example.com', and template model containing order_id and total fields

Bounce Management and Deliverability Monitoring

Monitor and manage email bounces to maintain sender reputation and high deliverability. The API provides bounce listing filtered by type (HardBounce, SoftBounce, SpamComplaint, etc.), individual bounce details with diagnostic info, and the ability to reactivate recipients who previously bounced. Delivery stats endpoint provides aggregate counts of sent, bounced, and complained messages for trend analysis.

Retrieve all HardBounce records from GET /bounces with type filter, then reactivate a specific bounced address using PUT /bounces/{bounceid}/activate

Email Analytics and Engagement Tracking

Track email engagement through open rates, click rates, and platform-specific breakdowns. The API provides aggregate statistics by time period, per-message open and click events, and breakdowns by email client, browser family, and geographic location. This enables data-driven decisions about email timing, content optimization, and audience segmentation based on actual engagement data.

Retrieve outbound open statistics from GET /stats/outbound/opens for the last 30 days and compare against click statistics from GET /stats/outbound/clicks

AI Agent Email Operations

Enable AI agents to send emails, monitor delivery health, and respond to engagement signals through Jentic. Agents discover sending and tracking operations via intent search, receive operation schemas with required fields, and execute without manual API documentation review. Jentic handles token management so agents focus on composing messages and interpreting delivery feedback.

Search Jentic for 'send a transactional email', load the Postmark batch send schema, and execute to deliver 10 notification emails with unique template variables

Key Endpoints

43 endpoints — the postmark api handles transactional email delivery with 43 endpoints covering sending (single, batch, and templated), bounce management, inbound message processing, outbound message search, delivery statistics, and template management.

METHOD

PATH

DESCRIPTION

POST

/email

Send a single email message

POST

/email/batch

Send a batch of up to 500 emails

POST

/email/withTemplate

Send an email using a template

GET

/bounces

List bounces filtered by type

GET

/stats/outbound

Get aggregate outbound delivery statistics

GET

/messages/outbound

Search outbound messages

GET

/templates

List all email templates

POST

/templates/validate

Validate a template before use

POST

/email

Send a single email message

POST

/email/batch

Send a batch of up to 500 emails

POST

/email/withTemplate

Send an email using a template

GET

/bounces

List bounces filtered by type

GET

/stats/outbound

Get aggregate outbound delivery statistics

Why though Jentic?

Three things that make agents converge on Jentic-routed access.

Credential isolation

Postmark Server Tokens are stored encrypted in the Jentic vault (MAXsystem). Agents receive scoped access tokens and never see the raw X-Postmark-Server-Token header value directly.

Intent-based discovery

Agents search by intent (e.g., 'send a transactional email') and Jentic returns matching Postmark operations with their input schemas, so the agent can compose and send emails without reading API documentation.

Time to first call

Direct Postmark integration: 2-4 days for auth, template setup, and bounce handling. Through Jentic: under 1 hour — search, load schema, execute.

Related APIs

Alternatives and complements available in the Jentic catalogue.

Complementary

Postmark Account-level API

Account-level API for managing servers, domains, and sender signatures that underpin email delivery

Use the Account API when you need to provision servers or configure domain authentication. Use this Server API for actual email sending and tracking.

Alternative

SendGrid Mail API

High-volume email delivery with marketing campaign features and IP pool management

Choose SendGrid when you need marketing email alongside transactional, dedicated IP addresses, or higher volume sending with IP warmup.

Alternative

SparkPost API

Email delivery API with predictive analytics and advanced deliverability tools

Choose SparkPost when you need predictive inbox placement, email validation, or high-volume sending with advanced deliverability insights.

FAQs

Specific to using Postmark API API through Jentic.

What authentication does the Postmark API use?

The Postmark API uses a Server Token passed in the X-Postmark-Server-Token HTTP header. Each server in your Postmark account has its own token. Through Jentic, this token is stored encrypted in the credential vault and agents receive scoped access without handling the raw token value.

Can I send batch emails with the Postmark API?

Yes. The POST /email/batch endpoint accepts an array of up to 500 messages in a single request. Each message can have its own recipient, subject, and body. For templated batch sends, use POST /email/batchWithTemplates which supports individual template models per message.

What are the rate limits for the Postmark API?

Postmark limits batch sends to 500 messages per request. Listing endpoints use count (max 500) and offset parameters for pagination. Overall sending rate depends on your account tier and server configuration. The API returns appropriate error codes when limits are exceeded.

How do I track email opens and clicks with the Postmark API through Jentic?

Install the SDK with pip install jentic, then search for 'track email open rates'. Jentic returns the GET /stats/outbound/opens operation. For per-message click data, search for 'get email click events' to find GET /messages/outbound/clicks/{messageid}. Execute with date range parameters to retrieve engagement metrics.

Can I process inbound emails with the Postmark API?

Yes. The API provides GET /messages/inbound to list received messages, GET /messages/inbound/{messageid}/details for full message content, PUT /messages/inbound/{messageid}/retry to reprocess failed messages, and PUT /messages/inbound/{messageid}/bypass to skip inbound rules for a specific message.

How do I validate a template before sending with it?

Use POST /templates/validate with your template content and a sample model object. The API checks for syntax errors and missing variables, returning validation results before you deploy the template to production. This prevents runtime rendering failures when sending to recipients.