# Email Deliverability Audit

Diagnostic audit for a running cold email program.

- Repository: https://github.com/growthenginenowoslawski/coldoutboundskills (797 stars)
- Category: Testing
- License: MIT
- Last updated: 2026-10-05
- Runs scripts: yes, review before use

## Install

Claude Code: `npx skills add growthenginenowoslawski/coldoutboundskills --skill email-deliverability-audit -g -a claude-code -y`
Codex: `npx skills add growthenginenowoslawski/coldoutboundskills --skill email-deliverability-audit -g -a codex -y`
Cursor: `npx skills add growthenginenowoslawski/coldoutboundskills --skill email-deliverability-audit -g -a cursor -y`
Gemini CLI: `npx skills add growthenginenowoslawski/coldoutboundskills --skill email-deliverability-audit -g -a gemini-cli -y`

## Description

Diagnostic audit for a running cold email program. Checks domain authentication (SPF/DKIM/DMARC), inbox health/reputation from Smartlead, bounce rate by inbox type, and optionally runs a spam placement test via Smartlead's Smart Delivery API. Outputs markdown report + CSV with per-domain/per-inbox scores and concrete action items. Use when reply rates drop, when bounces spike, when onboarding someone else's account, or as a weekly/monthly health check.

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

# Email Deliverability Audit

**If your positive reply rate is dropping and you don't know why, start here.** Most of the time the problem is deliverability, your emails aren't reaching inboxes. This skill tells you what's broken.

## What it checks

| Layer | What | How |
|---|---|---|
| DNS auth | SPF, DKIM, DMARC present on each sending domain | `dig` commands |
| Inbox health | Warmup status, reputation, blocks, connection failures | Smartlead email-accounts API |
| Volume health | Daily sent trending, capacity utilization | Smartlead analytics |
| Send + reply rate per inbox | Sent count, reply count, reply rate % over lookback period | Smartlead campaign analytics |
| Bounce rate | Per-inbox and per-domain bounce rate over last 30 days | Smartlead campaign analytics |
| Spam placement | Real inbox-vs-spam test via Smartlead Smart Delivery | optional |

## The 1% rule, and the floors that gate it

**A healthy domain replies at 1% or better after 200 emails sent.** Below 1% on a fair sample,
something is broken, and if it stays broken the domain gets cancelled.

The 1% rule is **one number**: the same 1% that flags a domain here is the line that retires it in
`/inbox-lifecycle-manager`. What separates "flag" from "cancel" is not a softer second threshold, it is the **floors**. Below a floor, the answer is "we don't know yet", which is a legitimate
output rather than a failure.

| Judgment | Floor before it counts |
|---|---|
| Reply rate | **200 sends** in the window |
| Bounce rate | **50 sends** |
| Bounce *composition* (which bucket) | **30 classified bounces for that domain** |
| Any cancel decision | **30 days of domain age**; unknown age counts as young |
| Placement test | 100-300 senders per test |

Reporting `0.00% reply` on 14 sends as a failure, or condemning a three-week-old domain that has
not finished ramping, is how healthy domains get killed.

The rest: https://github.com/growthenginenowoslawski/coldoutboundskills/blob/HEAD/skills/email-deliverability-audit/SKILL.md