# Resend setup for PopMCP

You end up pasting a single Resend API key that starts with `re_` and is shown once, at creation time.

- Auth: API credentials
- Setup time: 2 min
- API base URL: https://api.resend.com
- Credentials screen: https://resend.com/api-keys
- Provider docs: https://resend.com/docs/api-reference/introduction

## Before you begin

- Resend account. The free tier is enough.
- Membership of the Resend team with permission to create API keys
- A verified sending domain if you want to send from your own domain instead of onboarding@resend.dev

## Get your credentials

### 1. Open the API Keys page

Sign in at resend.com and click API Keys in the left sidebar, or go straight to `resend.com/api-keys`.

Screen: https://resend.com/api-keys

### 2. Click Create API Key

Press Create API Key at the top right of the page. A dialog opens with a name, a permission and a domain.

Screen: https://resend.com/api-keys

### 3. Name the key and pick a permission

Type `PopMCP` in Name, choose Full access for every Resend tool or Sending access for a send-only connection, then click Add. Sending access also lets you lock the key to one domain.

Screen: https://resend.com/api-keys

### 4. Copy the key straight away

Resend reveals the full `re_` key once. Click Copy before you close the dialog.

Screen: https://resend.com/api-keys

### 5. Paste the key into PopMCP

Paste the value into the PopMCP API key field and save.

## Fields PopMCP asks for

- API key (apiKey) [required]: Resend → API Keys → Create API Key. Choose Full access for all tools, or Sending access for send-only. Copy the key (shown once). Stored encrypted.

## Verify

PopMCP shows the Resend connector as Connected. Listing your domains returns the domains in that Resend team. A sending-only key returns a permission error on that tool instead, which still confirms the key is valid.

## Troubleshooting

### 401 Unauthorized, "API key is invalid"

Cause: The key was truncated on paste, or it was deleted from the Resend dashboard.

Fix: Create a fresh key on resend.com/api-keys and paste the whole `re_` string with no surrounding spaces.

### 403 restricted_api_key

Cause: A Sending access key was used for a tool that reads or writes domains, contacts or broadcasts.

Fix: Create a new key with Full access and reconnect.

### 403 validation_error, domain is not verified

Cause: You are sending from a domain that has not completed DNS verification.

Fix: Verify the domain under **Domains** in the Resend dashboard, or send from onboarding@resend.dev while testing.

### 429 rate_limit_exceeded

Cause: More than the default 10 requests per second per team.

Fix: Batch your sends or slow the calls down. Ask Resend support to raise the limit for high-volume accounts.

### You lost the key value

Cause: Resend never displays a key again after the creation dialog closes.

Fix: Remove the old key from the row menu under **More options**, then create a replacement.

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Source: https://www.docs.popmcp.com/docs/integrations/resend/