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The resend MCP adapter integrates Resend for reliable transactional email. Use it to notify users when workflows finish, send reports, and drive onboarding sequences — with a verified sender domain.

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Prerequisites

  • A Resend account with a verified domain (or Resend’s test domain for development)
  • A Resend API key with send permissions
  • A default From address on that verified domain
  • project_contributor access

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Connect in AgentRuntime

1

Verify your domain in Resend

In the Resend dashboard, add DNS records for your sending domain and wait for verification.
2

Create a connection

Go to Connections, click New custom connection, and create an API key connection, and paste your Resend API key. Optionally set FromEmail in the connection or MCP config profile.
3

Add resend MCP instance

Go to MCP, click Add instance for resend, wire your connection on Instance config, set the profile active, and save.
4

Send a test email

Run a workflow with mcp_call → send_email to yourself before wiring production notifications.

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What you can build

  • Workflow completion alerts — After a run succeeds or fails, send_email with run ID, step summary, and a link to Command Center.
  • Weekly digest — Postgres postgres_query for metrics → LLM narrative → send_email to stakeholders.
  • Human task reminders — When a human_task is assigned, email the assignee with task title and due date.
  • Audience sync reporting — list_audiences to verify list IDs before syncing contacts from ActiveCampaign or a form webhook.

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Tools

ToolDescription
send_emailSend an email through Resend
list_audiencesList audiences visible to the API key

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Example

{
  "id": "notify-complete",
  "type": "mcp_call",
  "name": "Email run summary",
  "tool_name": "send_email",
  "tool_args": {
    "to": "ops@example.com",
    "subject": "Workflow finished: {{input.workflow_name}}",
    "html": "<p>Run <strong>{{input.run_id}}</strong> completed.</p>"
  },
  "timeout_s": 30
}

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Configuration

KeyRequiredDescription
APIKeyYesResend API key
FromEmailYesVerified sender address (default From on send_email)
APIBaseNoResend API base URL (default production endpoint)
AudienceIDNoDefault audience for list/subscription tools

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Troubleshooting

IssueFix
Domain not verifiedComplete DNS verification in Resend before sending to external addresses
403 on sendFrom address must use a verified domain; check FromEmail in config
Emails in spamConfigure SPF, DKIM, and DMARC for your sending domain