Set up DMARC and see who's sending email using your brand's domain.
SMTP service

SMTP service: Quick and easy email delivery with Postmark.

Unlock the benefits for great email delivery in minutes.

What is SMTP?

Simple Mail Transfer Protocol (SMTP) is a widely supported standard for sending email. Most development frameworks support SMTP without the need for any extra libraries, making SMTP the quickest way to start sending transactional email from your web application.

Sending emails using SMTP.

Setting up your web application to send emails using SMTP couldn’t be easier. It’s as simple as copying some credentials into a config file and you’re ready to send.

Postmark supports TLS to secure data sent between your application and our servers.

Not sure whether to send using our API or SMTP service?
Check out the guide →

// Update the mail settings in your .env file.

# Save your Postmark Server API token to config/secrets.yml.
postmark_api_token: "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"

# Set Action Mailer to use SMTP in your config/application.rb file.
config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
  address:              '',
  port:                 587,
  domain:               '',
  user_name:            Rails.application.secrets.postmark_api_token,
  password:             Rails.application.secrets.postmark_api_token,
  authentication:       :plain,
  enable_starttls_auto: true

// Install express-mailer (
npm install express-mailer

// Add the SMTP credentials in your app.js file.
var app = require('express')(),
    mailer = require('express-mailer');

mailer.extend(app, {
  from: '',
  host: '',
  secureConnection: true,
  port: 587,
  transportMethod: 'SMTP',
  auth: {

# Add the SMTP credentials to your file.

# Send an email using the send_mail() function.
from django.core.mail import send_mail
send_mail('You email subject', 'Super awesome email content.', '', [''], fail_silently=False)

1. Log into the Craft admin area and go to "Settings" then "Email".

2. Set the "Transport Type" field to "SMTP".

3. Set the "Host Name" field to "".

4. Set the "Port" to "587".

5. Tick the "Use Authentication" checkbox.

6. Set both the "Username" and "Password" fields to your Postmark Server API Token.

7. Set the "Encryption Method" field to "TLS".

8. Test and save your changes.

Globally distributed SMTP service.

We maintain endpoints in several AWS Regions around the world. Depending on your location you will be routed to the closest endpoints to your servers for the fastest response times possible, resulting in very low latency.

Track messages through their entire lifecycle with custom metadata.

Specify metadata like invoice and customer IDs to identify messages at any point in their lifecycle. This information then becomes accessible through the Postmark API, webhooks, and web app.

You just need to add some custom headers when sending email using SMTP.

X-PM-Metadata-invoice-id: 123
X-PM-Metadata-customer-id: 4011
X-PM-Metadata-due-date: 2021-07-03

Group common message types using tags.

Use tags to easily identify similar messages using the Postmark web app or API. For example, you might use a welcome-email tag for all welcome emails sent by your application.

Access this feature by adding an X-PM-Tag header when sending email using SMTP.

X-PM-Tag: welcome-email

Developer friendly SMTP documentation.

Postmark’s clear and concise documentation makes it easy to start sending using SMTP. We cover advanced features like tags and custom metadata, as well as common pitfalls so you can troubleshoot any issues.

Postmark has a reputation for high quality. Even though there are several good companies, we were convinced by Postmark’s clear documentation and transparent roadmap. Further, building email infrastructure is really a partnership — we wanted to invest in a platform that would continue to grow along with our needs, not one that was fairly static and falling behind the technology curve.

Still have questions?

  • Abdullah Al-hennawy Abdullah
  • Anita Pericic Anita

Ask us anything! We’re eager to help you with any problem or question you have…

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