How to Set Up the Postmark Mailer in WP Mail SMTP

Would you like to use Postmark to improve email delivery for your WordPress site? This affordable solution integrates with our WP Mail SMTP plugin to help make sure emails sent from your website make it to your users’ inboxes.

In this tutorial, we’ll show you how to set up the Postmark mailer in WP Mail SMTP.

What Is Postmark?

Postmark is a service that prioritizes email delivery. Using its API, you can authenticate emails sent from your WordPress site so that they successfully arrive in recipients’ inboxes.

You can get started with Postmark for free with its developer plan. This option lets you send 100 test emails per month to try it out, and doesn’t require a credit card. Once you’re sure Postmark is the right mailer for you, you can upgrade to a paid plan to send more emails per month.

Although you can use any email address with Postmark, we recommend using one that is at your website’s domain (e.g., [email protected]). That way you can authenticate your domain (as discussed later in this tutorial), which provides more reliable email delivery than verifying an individual email address.

Configuring Your Postmark Account

First, you’ll need to set up your Postmark account. This includes choosing a plan and creating a Sender Signature.

Choosing a Postmark Plan and Signing Up for an Account

Head over to Postmark’s Pricing page to look over the available options. You can use the cost calculator to estimate your total monthly charges if you want to purchase a paid plan.

Otherwise, click on the Start Free Trial button at the bottom of the page to sign up for a developer plan.

Signing up for a free developer account with Postmark

Then create your login credentials and click Let’s get started.

Signing up for a Postmark account

At this point, Postmark will send a verification email to the address you provided. It will also automatically create an individual Sender Signature using this address.

Go ahead and open the email and click on the Confirm Sender Signature button.

Confirming Postmark account email and Sender Signature

If you want to use Postmark to send emails from a different address, don’t worry. We’ll show you how to create additional Sender Signatures shortly.

Requesting Account Approval

Finally, log in to your Postmark dashboard and look for the Request approval button in the toolbar.

Requesting account approval in Postmark

Postmark manually reviews each new account to make sure its platform isn’t being used to send emails that might damage its reputation.

You’ll need to fill out a bit of information, such as how many emails per month you intend to send and what you plan to use Postmark for.  Then submit your request.

Submitting an account approval request in Postmark

You can continue with the setup process below while you wait for approval (which typically takes 1 business day). However, you won’t be able to send any emails to addresses outside of your verified domain until after your account is approved.

Note: For more information on Postmark’s approval process, please see its official documentation on this topic.

Creating a Sender Signature

A Sender Signature is an individual email address or domain that is authorized in Postmark to send emails from your site.

To create a new Sender Signature, log in to your Postmark account and click on Sender Signatures at the top of your dashboard.

Accessing the Sender Signatures page in Postmark

Then click on the Add Domain or Signature button.

Adding a new domain or Sender Signature to Postmark

Adding a New Sender Signature

Note: Although you can get the Postmark mailer up and running with a Sender Signature for an individual email address, we recommend adding a domain instead to better ensure email delivery.

To send emails from a single email address, you can verify a Sender Signature. The email associated with your account will be verified during the signup process, but you can add as many additional addresses as you want.

First, click on the Add Sender Signature button.

Adding a new Sender Signature in Postmark

This will take you to a page with a short form to fill out. You’ll need to provide the sender’s name and email address.

Entering information for a new Sender Signature in Postmark

Click Create Signature when you’re ready. Postmark will send a verification email to the address you provided. Click the Confirm this Sender Signature button in the email to finish setting it up.

Adding a Domain

Note: You can verify a subdomain in Postmark and use an email address at that subdomain as the From Email in your WP Mail SMTP settings. This is usually the best setup for ensuring email delivery, as your subdomain’s reputation as an email sender is separate from your root domain’s.

To verify your sending domain, click on the Add Domain button.

Adding a domain in Postmark

This will open a popup window in which you’ll need to enter the domain you want to verify.

Entering the domain to verify in Postmark

Note: To verify your domain in Postmark, you will need to add DNS records to your domain. For guidance on this process, please see our tutorial on how to add DNS records to set up your mailer.

Click the Verify domain button to proceed. This will take you to a screen with the DNS records that you need to add to your DNS settings.

The DNS records you have to add to your DNS settings to verify a domain in Postmark

Keep this page open while you add the DKIM and Return-Path records to your DNS settings.

Note: Although Postmark does not require you to add the Return-Path record to your DNS settings to verify your domain, it is recommended to ensure email delivery.

Then come back to this screen and click on the corresponding Verify buttons for each record.

Verifying DNS records for Postmark

Note: It may take up to 48 hours for changes to your DNS settings to be recognized. If you try to verify your domain in Postmark and it doesn’t work, wait and try again. In the meantime, you can continue setting up WP Mail SMTP.

Once your domain has been successfully verified, you’ll see green checkmarks and “Verified” messages for each record as well as for your domain.

Verified DNS records for Postmark

Finding Your Postmark API Token

In order to connect your Postmark account to WP Mail SMTP, you will need an API token. You can find yours by clicking on Servers in your Postmark dashboard toolbar.

Accessing the Servers area of the Postmark dashboard

Then click on the name of the server you’re going to use to send emails. For this tutorial, we’ll be using the default (My First Server), but you can use any server you’ve created in Postmark.

Clicking on a server in Postmark to open its dashboard

Note: For more details on Postmark servers, check out the official documentation on managing servers.

In your server’s dashboard, click on API Tokens.

Accessing API Tokens for a Postmark server

This will bring up a screen with your server API Token. Leave this page open in a separate browser tab or window, as you’ll need to return to it later when configuring your WP Mail SMTP settings.

Copying a Postmark API Token

Setting Up WP Mail SMTP

Next, you’ll need to set up WP Mail SMTP on your WordPress site. First, make sure the plugin is installed and activated.

Then go to WP Mail SMTP » Settings. We’ll go over each of the options available here below.

From Email

The From Email should be the email address from which you want to send messages. If you set up a single Sender Signature in Postmark, this email address should match your Sender Signature. If you verified your domain, you can use any email at the domain you added in Postmark.

Adding a From Email to the WP Mail SMTP settings

You may also choose to check the Force From Email box. This will ensure all emails sent from your site use the same From Email.

Forcing the From Email in the WP Mail SMTP settings

From Name

The From Name is the name that will be shown as the sender on emails sent from your site. By default, it will match the name of your site, but you can set it to whatever you want.

Adding and forcing a From Name in the WP Mail SMTP settings

You can also check the Force From Name box to keep this setting the same for all emails sent from your site.


From the Mailer section of the Settings page, select Postmark.

Choosing the Postmark mailer in the WP Mail SMTP settings

Server API Token

Next, go back to the browser tab or window in which your Postmark account is open with your Server API Token. Copy the token, then paste it in the Server API Token field in your WP Mail SMTP settings.

Entering the Postmark Server API Token in the WP Mail SMTP settings

Message Stream ID (Optional)

Lastly, you can add a Message Stream ID from your Postmark account if you would like.

Postmark Message Streams enable you to organize the emails you send from different platforms. For example, if you had multiple WordPress sites, you could create a Message Stream for each of them in your Postmark account to keep their email data and tracking separate.

Note: For all the details on creating and using Message Streams, see Postmark’s documentation on sending emails through Message Streams.

To locate a Message Stream ID in your Postmark account, go to the Servers tab in your dashboard and click on your server’s name. On the following screen, you’ll see a list of existing Message Streams, including the Default Transactional Stream.

A list of Message Streams in Postmark

Click on the Message Stream you want to use. On the next screen, look for the Stream ID at the top of the page.

Locating a Postmark Message Stream ID

Copy this, then return to your WP Mail SMTP settings and paste it into the Message Stream ID field.

Adding a Postmark Message Stream ID to the WP Mail SMTP settings

If you leave this setting blank, WP Mail SMTP will use the Default Transactional Stream.

Once you’ve finished configuring WP Mail SMTP’s settings, make sure to save your changes.

Saving the WP Mail SMTP settings

Sending a Test Email

Finally, it’s important to send a test email from your site to make sure everything is working properly.

In your WordPress admin area, go to WP Mail SMTP » Tools and click on the Email Test tab.

Accessing the Email Test tool

Enter any email address that you have access to in the Send To field.

Note: If your Postmark account has not yet been approved, you can only send and receive emails from your verified Sender Signature. In this case, you’ll need to use your Sender Signature or an address at your verified domain as your Send To email for this test.

Then choose whether to send a plain text or HTML email. Unless you know you’ll only be sending plain text emails, we recommend leaving the HTML setting toggled ON.

When you’re ready, click on Send Email to send your test email. You should then see a success message.

The Email Test success message

Check your inbox for the test email.

A successful test email from WP Mail SMTP

That’s it! Now you know how to set up the Postmark mailer for WP Mail SMTP.

Next, would you like to set up email logging? Check out our tutorial on how to log emails for all the details.