Send your campaigns with Resend in MailerPress

This feature requires MailerPress Pro.

Resend is an email sending service. Connect it to MailerPress to send your campaigns, automation emails and test emails, and to track bounces (emails returned as undeliverable, for example because the address doesn’t exist).

1. Prepare your Resend account

1. Create an account on the Resend website or sign in.
2. In the Resend dashboard, go to Domains, click Add Domain and enter your domain (for example example.com). At your domain provider, add the DNS records Resend gives you (settings that prove you own the domain), then verify the domain in Resend.
3. Go to API Keys and create a key for MailerPress. Sending access is enough. Copy the key (it starts with re_): you won’t see it again. MailerPress uses this secret key to send through your Resend account.

2. Link your site with the Resend API

1. Go to MailerPress > Integrations and open the Email Service Providers tab.
2. In Other Providers, click Configure on the Resend card.
3. Paste your key in the Resend API key field.
4. Fill in Default sender email address and Default sender name. The address must use your verified Resend domain. Empty fields show your global default sender as a placeholder.
5. Click Save changes. The card moves to Configured Providers.
6. Turn on the card’s Enable toggle, then click Set as primary provider. The card shows the Primary badge: only the primary provider sends your emails.

3. Send a test email

1. On the Resend card, open the Actions menu (three dots) and click Send test email.
2. Enter a recipient in Send to and click Send.

You should receive an email with the subject “This is a Sending Method Test”. If the test fails, MailerPress shows the error returned by Resend:

• 401: the API key is invalid or missing.
• 403: the API key doesn’t have the necessary permissions, or the Resend account is suspended.
• 422: the sender address isn’t on a domain verified in Resend.
• 429: too many requests. If this happens during campaigns, lower the sending speed (see below).

4. Configure the sending speed

1. Go to MailerPress > Settings > Sending frequency, or click Adjust sending frequency on the Resend card.
2. Under Configuration Mode, choose Profile and select one of the Resend profiles below. You can also choose Automatic to let MailerPress pick a profile, or Manual to set your own batch size, interval and Rate limit (emails per second).
3. Click Save settings.

Profile	Emails per batch	Interval	Emails per hour
Prudent (Free plan – 100/day)	50	5 minutes	600
Balanced (Recommended)	75	5 minutes	900
Performance (Pro plans)	200	5 minutes	2,400

The profiles set the sending pace, not your Resend quota. On Resend’s free plan, stay within your daily allowance.

The sending frequency is saved for the provider that is primary at that moment. Set Resend as primary before you click Save settings. See How to change your sending frequency in MailerPress.

5. Enable bounce tracking

MailerPress learns about bounces through a webhook: a URL that Resend calls automatically when an email bounces.

1. On the Resend card, click Configure.
2. Turn on Enable bounce tracking. The setting is saved immediately.
3. Under Webhook URL, click Copy. The URL looks like https://example.com/wp-json/mailerpress/v1/esp/bounce/resend.
4. In the Resend dashboard, go to Webhooks and click Add Webhook.
5. Paste the URL in Endpoint URL, select the email.bounced event and create the webhook.

MailerPress only uses bounce notifications from Resend, so you don’t need other events such as email.complained.

Leave Webhook signing secret empty. MailerPress only records a bounce if it sent an email to that address through Resend in the last 30 days.

6. Track your bounces

Go to MailerPress > Audience and click the Bounced tab of the contact list. Campaigns only go to subscribed contacts, so bounced contacts no longer receive them.

To compare Resend with the other sending services, see Choose and configure your email sending service.