Cold Email Spar: 6 Claude sparring partners test your cold email before you send it (free Claude Code skill)

It's a free skill for Claude Code, and you don't need to write any code to use it. You copy a folder, prepare one input and type one line.

Who's on the panel

1. The Busy CEO: reads the subject and preview on a phone between meetings
2. The Gatekeeper: the assistant who decides whether it reaches the boss at all
3. The Spam Filter: checks the words for things that push mail into spam or promotions
4. The Skeptic: has seen every template and spots fake personalisation
5. The Happy Customer Elsewhere: already uses something for this and needs a reason to reply
6. The Champion: the right person, who would forward it inside the company if it's easy

Each one votes REPLY, IGNORE or DELETE, scores the email out of 10, and gives one reason and one fix. They don't see each other's answers: in Claude Code each one runs as its own Claude, with its own fresh context, all 6 at the same time.

What you get

A report short enough to fit in one screenshot:

• who replies, who ignores and who deletes
• a content-only spam check
• the knockout punch: the one problem costing you the most replies
• a rewritten email (90 words or fewer) ready to paste, with two extra subject lines
• a day-3 follow-up line

The last line of the report says how the panel actually ran, so you always know whether you got 6 separate Claudes or one Claude doing 6 passes.

Before you start

• Claude Code. It works in the Claude desktop app (the Code tab) or in a terminal.
• A paid Claude plan or API credit. Claude Code needs a Claude Pro ($20 a month) or Max plan, or pay-as-you-go credit from the Claude Console. Each run starts 6 reviewers, so it uses more of your plan's usage than a single chat message.
• The skill folder. Download it free below. The skill file costs nothing; running it is what needs Claude Code.
• About 10 minutes for the first run, then a minute or two per run after that.

Step 1: Put the folder in place

Unzip the download. Copy the whole cold-email-spar folder (not just the files inside it) into your Claude skills folder:

• Mac: ~/.claude/skills/ (in Finder press Cmd+Shift+G and paste ~/.claude/skills)
• Windows: C:\Users\YOUR-NAME\.claude\skills\ (paste %USERPROFILE%\.claude\skills into the File Explorer address bar)

If the skills folder doesn't exist yet, create it.

Step 2: Get your cold email ready

Copy the email you want to test: subject line, body and signature. Add one line on who it's going to, for example "marketing director at a 50-person software company".

Step 3: Run it

Open Claude Code and start a new session so it picks up the new skill. Then type /cold-email-spar followed by the email (or the path to a text file or screenshot) and who it's for, then press Enter. For example:

/cold-email-spar "/Users/you/Desktop/outreach.txt" to: owners of local gyms

It takes a minute or two. If Claude asks for permission to read your files or to start the sparring partners, say yes.

What it can't do

• The spam check reads the words only. Whether mail reaches the inbox depends mostly on your sending domain's setup and reputation, which nobody can see from the text. The report says this every time.
• It won't invent personalisation. Where the email needs a detail about the person you're writing to, the rewrite leaves a [bracket] for you to fill in.
• It doesn't send anything. It reviews the email; you send it from your own inbox.

Using the Claude.ai chat app instead

You can upload the skill as a zip in the Claude.ai app (Settings, then Capabilities, then Skills). Chat can't start subagents, so there one Claude plays all 6 sparring partners one after another. It still works, and the report's last line says so.