---
ref: workflow:resend-to-unopened
title: Win a second open with a subject-line resend
author: thedogwiththedataonit
tools: [tool:brew/create-audience-from-events, tool:anthropic/create-message, tool:brew/send-email]
tags: [capability:build-audience, capability:send-email, capability:write-copy, channel:email, has:api, has:cli]
updated: 2026-09-27
---

# Win a second open with a subject-line resend

Set up the tools below, then run the steps in order for the user.

## Inputs

Ask the user for these before you start.

- `send_id`: the Brew send to follow up
- `email_id`: the email it sent
- `original_subject`: its subject line
- `wait_days`: how long to wait after the first send, e.g. 3

## Set up

### Brew (tool:brew/create-audience-from-events, tool:brew/send-email)

Use the first option your agent supports.

#### MCP (official, remote)

Add this server to your agent's MCP settings, then sign in when asked.

```json
{ "mcpServers": { "brew": { "url": "https://brew.new/api/mcp" } } }
```

- Create an audience from email events: call the MCP tool `create_audience_from_events`
- Send an email: call the MCP tool `send_email`

#### CLI (official)

Install the command, then confirm it runs.

```sh
brew install getbrew/tap/brew-cli
brew-cli --version
```

- Create an audience from email events: run `brew-cli audiences from-events`
- Send an email: run `brew-cli emails send`

Set `$BREW_API_KEY` in your environment first (get a key: https://brew.new/settings/api).

### Create a message (Anthropic, tool:anthropic/create-message)

Use the first option your agent supports.

#### CLI (official)

Install the command, then confirm it runs.

```sh
curl -fsSL https://claude.ai/install.sh | bash
claude --version
```

Run `claude -p`.

#### API (official)

- Base URL: https://api.anthropic.com
- Endpoint: `POST /v1/messages`
- Auth: send the header `x-api-key: $ANTHROPIC_API_KEY`
- Get a key: https://platform.claude.com/settings/keys

Make one read-only call to each tool to confirm access.

## Steps

1. **Segment** with Create an audience from email events (Brew). Build an audience of the contacts in `send_id` who have not opened after `wait_days`, and wait until it has built.
2. **Rewrite** with Create a message (Anthropic). Write two alternatives to `original_subject` that make a different promise. Show them to the user.
3. **Resend** with Send an email (Brew). Send `email_id` with the chosen subject line to that audience, after the user approves.

## Done when

- Only unopened contacts received the resend.
- The user has the number of contacts it went to.

## Rules

- Only use the tools listed above.
- Ask the user before anything that sends messages, costs money, or changes data.
- Never print API keys.