Resend

Resend — Email Skill

When to use

Use this skill when a squad needs to send emails — welcome messages, notifications, reports, newsletters, or any transactional/marketing email. Resend handles delivery so the squad only needs to compose the content and call the MCP tools.

Instructions

Sending a single email

1. Prepare from, to, subject, and body (HTML or plain text).
2. Call the Resend MCP send_email tool.
3. Check the response for a successful id — that confirms the email was queued.

Sending a batch

1. Build an array of email objects (same fields as single send).
2. Call the Resend MCP batch_send_emails tool.
3. Each item in the response will have its own id or error.

Attachments

Pass attachments as an array with filename, path (local file), url, or content (base64).

Scheduling

Include a scheduled_at field (ISO 8601 datetime) to schedule future delivery.

Best practices

• Validate from against a verified domain before sending — Resend rejects unverified senders.
• Keep subject lines under 80 characters for better deliverability.
• For batch sends, group by shared content to reduce payload size.
• Always check the response for errors and surface them to the user rather than silently failing.
• When composing HTML emails, keep the markup simple — most email clients ignore complex CSS.

Available operations

• Send Email — Single email with HTML/text body, attachments, CC/BCC, reply-to
• Batch Send — Multiple emails in one call
• Schedule Email — Queue an email for future delivery
• List/Get Emails — Check delivery status of sent emails
• Cancel Email — Cancel a scheduled email before it sends
• Manage Contacts — Create, list, update, and remove contacts from audiences
• Manage Domains — Add and verify sender domains

Setup

1. Create a free account at resend.com
2. Generate an API key (starts with re_)
3. Add a verified sender domain (or use Resend's shared onboarding@resend.dev for testing)
4. Set RESEND_API_KEY in your .env file