Postmark API

api.postmarkapp.com · Communication

Communication API Key Free Tier Email Transactional Email Communication

High-deliverability transactional email API — fast delivery, detailed open/click tracking, bounce handling, templates, and inbound email parsing. 98.7% inbox rate. Free: 100 emails/month.

Authentication

API Key Server token from postmarkapp.com. Pass as X-Postmark-Server-Token header.

Sample Requests

POST Send email

Send a transactional email via Postmark.

https://api.postmarkapp.com/email

Hover any highlighted part to learn what it does

Headers — extra info sent with the request

Accept	application/json
Content-Type	application/json
X-Postmark-Server-Token	YOUR_TOKEN

Request Body — data you're sending

{
  "To": "[email protected]",
  "From": "[email protected]",
  "Subject": "Hello from Postmark",
  "TextBody": "Testing Postmark API!",
  "MessageStream": "outbound"
}

curl -X POST "https://api.postmarkapp.com/email" \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -H "X-Postmark-Server-Token: YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"To":"[email protected]","From":"[email protected]","Subject":"Hello from Postmark","TextBody":"Testing Postmark API!","MessageStream":"outbound"}'

import requests
headers = {
    "Accept": "application/json",
    "Content-Type": "application/json",
    "X-Postmark-Server-Token": "YOUR_TOKEN"
}
data = {
    "To": "[email protected]",
    "From": "[email protected]",
    "Subject": "Hello from Postmark",
    "TextBody": "Testing Postmark API!",
    "MessageStream": "outbound"
}
response = requests.post(
    "https://api.postmarkapp.com/email",
    headers=headers,
    json=data,
)
print(response.json())

const url = 'https://api.postmarkapp.com/email';

const response = await fetch(url, {
  method: 'POST',
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json',
    'X-Postmark-Server-Token': 'YOUR_TOKEN'
  },
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
  "To": "[email protected]",
  "From": "[email protected]",
  "Subject": "Hello from Postmark",
  "TextBody": "Testing Postmark API!",
  "MessageStream": "outbound"
}),
}); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
	"bytes"
	"encoding/json"
)

func main() {
	targetURL := "https://api.postmarkapp.com/email"
	jsonData, _ := json.Marshal({"To":"[email protected]","From":"[email protected]","Subject":"Hello from Postmark","TextBody":"Testing Postmark API!","MessageStream":"outbound"})
	req, _ := http.NewRequest("POST", targetURL, bytes.NewBuffer(jsonData))
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("X-Postmark-Server-Token", "YOUR_TOKEN")
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://api.postmarkapp.com/email")

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Post.new(uri)
req["Accept"] = "application/json"
req["Content-Type"] = "application/json"
req["X-Postmark-Server-Token"] = "YOUR_TOKEN"
req["Content-Type"] = "application/json"
req.body = "{\"To\":\"[email protected]\",\"From\":\"[email protected]\",\"Subject\":\"Hello from Postmark\",\"TextBody\":\"Testing Postmark API!\",\"MessageStream\":\"outbound\"}"

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://api.postmarkapp.com/email";
$opts = ["http" => [
    "method" => "POST",
    "header" => implode("\r\n", [
        "Accept: application/json",
        "Content-Type: application/json",
        "X-Postmark-Server-Token: YOUR_TOKEN",
        "Content-Type: application/json"
    ]),
    "content" => json_encode({"To":"[email protected]","From":"[email protected]","Subject":"Hello from Postmark","TextBody":"Testing Postmark API!","MessageStream":"outbound"}),
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

Postman Setup Guide

Get Postman ↗

Sign up at postmarkapp.com — 100 free emails/month forever
Get server token from your Postmark account
Set X-Postmark-Server-Token: YOUR_TOKEN header
Use POSTMARK_API_TEST as token for testing without sending real emails
MessageStream: outbound (transactional) or broadcasts (bulk)

Open documentation ↗