# Send Cold Email

Send cold email and run outbound email campaigns from an agent with Sendsets.

- Repository: https://github.com/hashgraph-online/awesome-codex-plugins (1479 stars)
- Category: Testing
- License: Apache-2.0
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add hashgraph-online/awesome-codex-plugins --skill send-cold-email -g -a claude-code -y`
Codex: `npx skills add hashgraph-online/awesome-codex-plugins --skill send-cold-email -g -a codex -y`
Cursor: `npx skills add hashgraph-online/awesome-codex-plugins --skill send-cold-email -g -a cursor -y`
Gemini CLI: `npx skills add hashgraph-online/awesome-codex-plugins --skill send-cold-email -g -a gemini-cli -y`

## Description

Send cold email and run outbound email campaigns from an agent with Sendsets. Connect or check sending mailboxes, turn a lead list (CSV or inline) into a multi-step email sequence with follow-ups, validate merge fields, send a test, launch, and read and answer replies. Use when the user asks to send cold emails, email a list of prospects or leads, run an outreach or outbound sequence, or follow up with contacts by email.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Send cold email with Sendsets

Sendsets is a cold email API for agents. Work through the Sendsets MCP tools when they are connected (`list_mailboxes`, `create_campaign_draft`, `add_campaign_step`, `add_contact`, `start_campaign`, `list_threads`, `send_reply`, ...). Otherwise use the `sendsets` CLI with `--json`. Both act on the same workspace.

Not connected yet? Pick one:

- MCP: `claude mcp add --transport http sendsets https://api.sendsetsapi.com/v1/mcp` (OAuth sign-in in the browser; other clients use the same URL)
- CLI: install with `brew install addisonhoff/tap/sendsets` (macOS, Linux) or `scoop bucket add sendsets https://github.com/AddisonHoff/homebrew-tap` then `scoop install sendsets` (Windows). Without a package manager, download the archive for your platform and `checksums.txt` from https://github.com/AddisonHoff/sendsets-releases/releases/latest, check the archive against `checksums.txt`, and unpack the `sendsets` binary onto PATH. Then `sendsets login --hostname sendsetsapi.com` (it prints a code and URL for the user to approve) and `sendsets doctor --json`

A new workspace is free for up to 10 mailboxes: https://app.sendsetsapi.com/auth/register

## 1. Senders

`sendsets mailbox list --json`. With no mailbox, connect one:

- Gmail or Google Workspace: the user creates an app password at https://myaccount.google.com/apppasswords and enters it themselves at https://app.sendsetsapi.com/app/emails (Connect mailbox, then Gmail). Never ask for a mailbox password in chat and never put one on a command line, where it lands in shell history and the process list
- Microsoft 365: `sendsets mailbox add --provider outlook` prints a consent link for the user
- Anything else over SMTP/IMAP: the user connects it in the same dialog with their host, port and password

Never guess credentials. A fresh mailbox should warm up first (`sendsets mailbox warmup enable MAILBOX_ID`) and start around 10 to 20 cold emails a day.

## 2. The campaign

The rest: https://github.com/hashgraph-online/awesome-codex-plugins/blob/HEAD/plugins/AddisonHoff/sendsets/skills/send-cold-email/SKILL.md