How to send email with Postmark

Knock integrates with Postmark to send email notifications to your users. This page describes how to get started with Postmark in Knock, including necessary provider configurations and additional data you can pass through to Postmark.

• Attachments support
• Delivery tracking
• Bounce Support
• Knock link and open tracking
• Postmark link and open tracking
• Per environment configuration
• Sandbox mode

You can create a new Postmark channel in the dashboard under the Channels and sources page in your account settings. From there, you'll need to configure the channel for each environment you have.

Configure the following settings per environment. Navigate to Channels and sources in your dashboard account settings and select your Postmark channel. Under Environment configurations, click the environment you'd like to configure to expand its settings, then click "Save changes" when you're done. Expand Advanced for additional options, including overrides and conditions.

Knock sends the following attributes along with your emails:

• Metadata.sender: always set to knock.app
• Metadata.knock_message_id: the ID of the message this email is associated with
• Metadata.knock_recipient_id: the Knock ID of the recipient this email is being sent to
• Tag: the key of the workflow this message was generated from

You can learn about the role of these Postmark attributes in the Postmark API documentation.

In order to send an email notification you'll need a valid email property set on your recipient.

When enabled, Postmark will send delivery status updates directly to Knock via webhooks, allowing you to track the full lifecycle of your email messages in real-time.

Before enabling delivery status webhooks, you need:

1. A verified sender signature or domain in Postmark
2. A Postmark channel configured in Knock (see the getting started section above)
3. Access to your Postmark server webhook settings

When delivery status webhooks are enabled for Postmark, Knock will update message statuses based on these Postmark webhook events:

Postmark Event Type	Knock Status	Description
Delivery	delivered	The email was successfully delivered to the recipient's mail server
Bounce	bounced	The email bounced due to invalid recipient or domain

When a recipient marks an email as spam, Postmark sends a SpamComplaint webhook event to Knock. Knock records a message.complaint event on the message. A complaint does not change the message's delivery status, because the message was delivered before the recipient reported it.

You can see complaint events in the message timeline in the Knock dashboard, and subscribe to them with outbound webhooks. Postmark deactivates the recipient's address after a spam complaint, so later sends to that address bounce.

If delivery status updates aren't appearing in Knock:

1. Check webhook configuration. Verify both the Delivery and Bounce webhooks are configured with the correct Knock webhook URL in your Postmark server settings.
2. Verify sender signature. Ensure you're sending from a verified sender signature or domain in Postmark.
3. Check Postmark activity. Review the Activity page in Postmark to ensure emails are being sent successfully.

We provide full support for overriding the payload of your email notifications. This enables you to customize the API request that Knock sends to Postmark on your behalf.

Knock does not target a specific MessageStream when sending your transactional email notifications to Postmark. This means that Postmark defaults your notifications to the "outbound" transactional stream.

For marketing use cases such as newsletters or product updates sent to large recipient lists, and particularly when leveraging Knock's broadcasts feature, we recommend following Postmark's best practices for sending promotional messaging via a separate MessageStream.