Postmarkapp Postmark API
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AI ReadinessAI-Aware (A-)72/100
Community OpenAPI document · agent-readyCommunicationsEmail DeliveryapiKey43 EndpointsREST
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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.
Use for: I need to send a transactional email with a template, I want to check the delivery status of a sent message, List all hard bounces from the last 7 days, Retrieve open and click statistics for outbound emails
Not supported: Does not handle account infrastructure setup, domain verification, or sender signature management - use for email sending and delivery tracking only.
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.
Install Jentic One Beta
Connect the Postmark API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Postmark API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fpostmarkapp.com%2Fpostmark-api" | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fpostmarkapp.com%2Fpostmark-api" | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with Postmark 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
Manage email templates with validation before deployment
Monitor bounce rates by type and reactivate deactivated recipients
Configure inbound processing rules with trigger-based routing
Use Cases
Patterns agents use Postmark 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
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
GET
/messages/outbound
Search outbound messages
GET
/templates
List all email templates
POST
/templates/validate
Validate a template before use
Jentic AI Readiness Score
This API is usable in Jentic One now. Its AI-readiness score against Jentic's framework shows where it stands today and where improvements would make it even easier for agents to use.
P
Postmark API
- AI-Aware (A-)72/100
89
Foundational Compliance67
Developer Experience & Jentic Compatibility47
AI-Readiness & Agent Experience94
Agent Usability100
Security100
AI DiscoverabilityPowered by JenticScoring Framework 1.0.0 | Scoring Engine 0.4.0
Show dimension breakdown
89
Foundational Compliance
Base layer of spec validity and structural soundness.
Grade: ASignals: 4
96%
Lint Results
Aggregated quality score from linter diagnostics, weighted by severity.
100%
Resolution Completeness
Percentage of `$ref` references that resolve successfully.
100%
Specification Validity
Checks whether the API description parses successfully and conforms to its declared specification (e.g., OpenAPI).
60%
Structural Integrity
Structural correctness score based on schema issues using logarithmic dampening.
67
Developer Experience & Jentic Compatibility
Clarity, completeness, and ingestion readiness for developers and tooling.
Grade: B+Signals: 4
0%
Example Density
How richly the API is illustrated with examples.
100%
Example Validity
Percentage of examples that conform to their schemas.
75%
Response Coverage
Percentage of operations with complete response definitions (success, client error, server error).
93%
Tooling Readiness
Health of API ingestion, bundling, and resolution within Jentic pipelines.
47
AI-Readiness & Agent Experience
Semantic breadth, depth, and agent comprehension for AI systems.
Grade: D+Signals: 4
41%
Description Coverage
Coverage of descriptions across API elements.
0%
Error Standardization
Coverage of RFC 9457 Problem Details for error responses.
95%
OperationId Quality
Coverage, uniqueness, and casing consistency of operationIds for AI inference.
53%
Summary Coverage
Coverage of summaries across operations/tags/info.
94
Agent Usability
Functional utility, complexity comfort, and AI orchestration readiness.
Grade: A+Signals: 1
94%
Complexity Comfort
Agent comfort level based on API operational and structural complexity.
100
Security
Trust, risk posture, and security compliance.
Grade: A+Signals: 1
100%
Authentication Strength
Average quality of security schemes based on authentication method strength (weakest link for OAuth2).
100
AI Discoverability
Findability, semantic richness, and reasoning readiness.
Grade: A+Signals: 1
100%
Descriptive Richness
Clarity and depth of descriptions across API elements.
Score it yourself
Every API in the directory is allowlisted, so you can re-score it with no key required.
npx @jentic/api-scorecard-cli score <openapi-url>Why Jentic?
What agents get from Jentic-routed access to this vendor.
Setup
Wiring the Postmark API by hand means setting up its X-Postmark-Server-Token header auth, pointing at api.postmarkapp.com, and building your own retry and bounce-polling logic. Through Jentic you install once, import the Postmark API from the API Directory, store the server token once, and your agent calls it.
Permission scoping
Postmark takes the send target in the request body rather than the URL path, so scoping is by operation: you limit the agent to the operations it needs, such as sending email or reading outbound stats and bounces. Because you pick that set, template validation or batch sending are only included if you add them.
Credential isolation
Your Postmark server token is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.
Intent-based discovery
Agents search Jentic by intent such as 'send a transactional email' or 'check recent bounces', and Jentic returns the matching Postmark operation with its input schema so the agent calls the right endpoint without browsing the reference docs.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Postmark 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.
Can I limit what my agent is allowed to do with the Postmark API?
Yes. Because your Jentic One instance is self-hosted, you set the rules that decide which Postmark operations your agent may call and which server token it uses. Postmark takes the send target in the request body rather than the URL path, so scoping is by operation: you can allow the agent to send email (POST /email) and read outbound stats (GET /stats/outbound) and bounces (GET /bounces) while withholding everything else. Batch sending (POST /email/batch) and template validation (POST /templates/validate) are included only if you add them to the agent's allowed set.
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