Resend is a developer-first email API launched in 2023 that has grown rapidly in the JavaScript ecosystem thanks to a clean SDK, React Email integration, and a modern dashboard. The unsubscribe mechanism uses a merge variable inside Broadcast templates, and Resend handles RFC 8058 compliance automatically for every Broadcast send. For pure transactional sends via the /emails endpoint, the List-Unsubscribe headers must be added manually via the headers parameter of the send request. Suppression is per Audience, which maps to the concept of a mailing list in older ESPs. This guide covers the tag, the Broadcasts model, and the transactional header injection pattern.
Resend unsubscribe link
| Tag syntax | {{{RESEND_UNSUBSCRIBE_URL}}} |
| Placement | Auto-embedded in Broadcast footer, manual for transactional API |
| Scope | Per Audience (mailing list) |
| Config path | Audiences > Manage audience |
| RFC 8058 one-click | Yes for Broadcasts, manual header for transactional API |
How to add the unsubscribe tag in Resend
Place the merge tag exactly as shown below in the email template. Resend replaces it at send time with a signed URL scoped to the recipient and campaign.
{{{RESEND_UNSUBSCRIBE_URL}}}For custom HTML templates, wrap the tag in an anchor to render a proper hyperlink in the delivered email:
<a href="{{{RESEND_UNSUBSCRIBE_URL}}}">Unsubscribe from this list</a>Auto-embedded in Broadcast footer, manual for transactional API
Yes for Broadcasts, manual header for transactional API The recipient's mailbox provider (Gmail, Yahoo) uses the List-Unsubscribe-Post header to expose the native one-click button on the message. Requires domain authentication with DKIM and DMARC.
Resend requires you to attach an Audience to a Broadcast for the unsubscribe URL merge variable to resolve. Sending a Broadcast without an Audience assigned renders the variable as an empty string, silently failing RFC 8058 compliance.
Testing your Resend unsubscribe link
- Send a test message to a controlled Gmail address you own via the Resend campaign preview action
- Click the footer unsubscribe link and confirm the opt-out on the landing page
- Check the subscriber or contact record: the status should be Unsubscribed within seconds
- Verify the RFC 8058 headers in Gmail: open the message, click three dots, then Show original. Look for
List-UnsubscribeandList-Unsubscribe-Post: List-Unsubscribe=One-Click
Want the full 222-platform reference?
See the pillar guide with the compliance landscape, the RFC 8058 deep dive, and the unsubscribe tag for every ESP: How to add an unsubscribe link: the complete 2026 guide →
Resend and modern transactional email
Resend is a developer-focused email API founded in 2023, positioned as a modern alternative to SendGrid and Postmark for transactional email. Its unsubscribe support is optional at the message level: developers include the List-Unsubscribe header via the Resend API when sending marketing messages, and omit it for pure transactional flows (receipts, notifications, password resets). Resend also supports the {{RESEND_UNSUBSCRIBE_URL}} template variable for React Email components.
Broadcast API for marketing
Resend Broadcast API is designed for marketing sends and includes automatic unsubscribe handling. Broadcasts inject the RFC 8058 headers (List-Unsubscribe and List-Unsubscribe-Post) automatically, and unsubscribed contacts are added to the account-wide suppression list that blocks future marketing sends. Transactional messages sent through the standard Send API do not include these headers by default, matching the standard convention that transactional messages are outside the opt-out scope.
Domain authentication and headers
Resend requires domain verification (SPF, DKIM) before sending, which means RFC 8058 headers work correctly from the first send once the domain is set up. The verification flow is streamlined compared to older platforms: adding DNS records and verifying takes typically 10-15 minutes. This aligns with Resend developer-first positioning: authentication is a prerequisite for any send, not an optional configuration step.
Suppression list integration
Resend maintains an account-wide suppression list that automatically includes hard-bounced addresses and marketing unsubscribes. Developers can query and modify the list through the Resend API, which is useful for reconciling suppressions with external systems (user databases, CRM tools). Attempting to send a marketing message to a suppressed address fails at the API level with a clear error, preventing accidental sends. This hard-blocking design is why Resend suppression enforcement is a key deliverability feature.
About the Author
Alaa · LinkedIn
Email infrastructure specialist with 8+ years of hands-on experience in SMTP, deliverability, and email verification. I’ve configured and troubleshot mail systems across Postfix, Exchange, and cloud relays, managed IP reputation and warmup campaigns, and built verification pipelines processing millions of addresses. My work spans DNS authentication (SPF, DKIM, DMARC, BIMI), bounce handling, blocklist monitoring, and compliance frameworks including CAN-SPAM and GDPR. I write every article on SMTPedia to give email professionals, developers, and marketers the accurate, RFC-grounded reference they need.
About SMTPedia
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