Set Up Resend

Resend is a simple option for sending email through an API. To connect Resend, add an API key, verify your sending domain, and configure one webhook endpoint. Mailrith uses the webhook endpoint to update subscriber statuses automatically after bounce and complaint events.

7 min read

Mailrith email delivery connections page showing connected services with action controls. — The Email Delivery Connections page lists every connected service. From here you can add a connection, send a test email, view delivery-event links, and assign connections to workspaces.

Before You Start

Resend connects to Mailrith with an API key and a verified sending domain. Before you create the connection, make sure you have:

A verified domain in Resend: your From email's domain must be verified in Resend and ready to send.
A Resend API key: the key Mailrith will use to send email through Resend.
A sender address: the From email subscribers will see in their inboxes.
Webhook access: access to Resend webhook settings so Resend can send bounce and complaint events back to Mailrith.

If your domain is still being verified, wait until Resend shows your domain as ready before you test the connection in Mailrith. An API key cannot send email successfully from a domain that Resend has not approved.

Mailrith Fields

In Mailrith, click Email Delivery Connections in the left sidebar, click Create Connection, choose Resend in Select Email Delivery Service, and complete these fields in Connect Email Delivery Service:

Connection name: an internal label, such as "Resend Product Updates".
API Key: the Resend key Mailrith uses for sending.
From name: the sender name subscribers see.
From email: an email address on a verified Resend domain.
Workspaces: the Mailrith workspaces that can use this connection.

Mailrith email delivery connections page showing connected provider rows — After saving the Resend connection, use the row actions for test sending and webhook setup.

Resend Setup

In Resend, verify the sending domain you plan to use for the From email.
Create a new Resend API key, or copy an existing active API key.
In Email Delivery Connections, click Create Connection, choose Resend, and paste the API key.
Enter the From name, From email, and workspace assignments for the connection.
Click Save, then use Send Test Email from the connection row to confirm Mailrith can send through Resend.

If the test fails, confirm that Resend shows your domain as verified, the API key is active, and the From email uses that verified domain.

Webhooks and Test Send

Resend can send bounce and complaint events to Mailrith through one webhook URL.

In Mailrith, click Email Delivery Connections, click Webhooks on the Resend connection, and copy the delivery-event webhook URL for that connection.
In Resend, open the webhook settings.
Add the Mailrith URL as the webhook endpoint.
Enable bounced and complained email events so Resend sends both event types to Mailrith.
Save the webhook, then monitor webhook deliveries after test or live sends and confirm Resend reports successful deliveries to the Mailrith endpoint.

Delivery-event webhooks let Mailrith update subscriber statuses after Resend reports a bounce or complaint. Without these webhooks, subscribers who bounced or complained may stay active until you update their statuses another way.

Need Help?

Reach out to the Mailrith team if you need help with anything.

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