Email Deliverability Audit

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 — core domain-health threshold

A healthy domain should have an overall reply rate of at least 1% after 200 emails sent.

Below 1% after 200+ sends is a red flag — something is broken. The audit explicitly checks this and flags any domain or inbox that:

• Has sent ≥200 emails in the lookback window
• Has an overall reply rate 3%, list is the problem)
• Inbox hasn't warmed enough (check warmup status)

Below 200 sends: too early to judge. The rule needs sample size.

When to use

• Reply rate dropped by >30% week-over-week → run the full audit
• Bounces spiked above 2% → run auth + spam-placement checks
• Before scaling a campaign (make sure infrastructure is ready)
• Monthly as routine hygiene
• When taking over a Smartlead account you didn't set up

Inputs

• SMARTLEAD_API_KEY (env)
• Optional: scope the audit
• --client-id=X (for sub-clients)
• --campaign-id=X (audit only one campaign's inboxes)
• --domain=example.com (audit only one domain)
• --tag=active (audit only inboxes tagged active)

Steps

1. Pull the inbox inventory

npx tsx scripts/audit-inboxes.ts --all --out=/tmp/audit/inboxes.csv

Outputs per inbox: id, email, domain, warmupstatus, reputation, maxwarmup/day, senttoday, smtpok, imapok, isblocked, tags.

2. Check domain authentication

npx tsx scripts/check-domain-auth.ts --from-csv=/tmp/audit/inboxes.csv --out=/tmp/audit/auth.csv

For each unique domain, runs:

dig TXT  +short          # SPF
dig TXT default._domainkey. +short    # DKIM (Zapmail uses "default")
dig TXT _dmarc. +short   # DMARC

Outputs: domain, spfpresent, spfstrict, dkimpresent, dmarcpresent, dmarc_policy (none/quarantine/reject).

3. Pull sent + reply + bounce metrics per campaign/inbox

npx tsx scripts/audit-performance.ts --days=30 --out=/tmp/audit/performance.csv

Walks all active campaigns, pulls per-inbox analytics for the last 30 days. Output columns: inbox_id, email, domain, type, tags, sent, replies, bounces, reply_rate_pct, bounce_rate_pct, flag_low_reply, flag_high_bounce.

Flagged automatically:

• flag_low_reply = TRUE if sent ≥200 and replyratepct 3.0

4. (Optional) Run a Smart Delivery spam placement test

npx tsx scripts/run-spam-test.ts --campaign-id=12345 --senders=100 --out=/tmp/audit/spam-test.json

This creates a real inbox-placement test via Smartlead's Smart Delivery API:

• Uses the only available provider pools: G Suite + Office365 (provider_ids 20, 21)
• Sends to ~200 seed mailboxes with 100 of your senders
• Waits for completion (5-20 min)
• Pulls: providerwise, spam-filter-details, dkim-details, spf-details, blacklist

Output shows: what % lands in Inbox vs Spam vs Promotions, broken down by your sender and the receiver provider. This is the ground truth.

5. Synthesize the report

npx tsx scripts/generate-report.ts --audit-dir=/tmp/audit --out=/tmp/audit/report.md

Produces a markdown report like:

# Deliverability Audit — 2026-04-17

## Summary

- 80 inboxes audited across 40 domains
- 3 inboxes blocked (4% of fleet)
- 5 domains missing DKIM
- 2 domains with DMARC policy=none (no enforcement)
- Fleet performance (last 30d):
    Sent:           42,384
    Replies:          523
    Overall reply rate: 1.23% (PASS — above 1% threshold)
    Bounces:           382
    Bounce rate:      0.90% (PASS — below 2%)
- 4 inboxes failed the 1% rule (sent ≥200, reply rate 3%** — Red. Verify the list (MillionVerifier), consider pausing.
- **>5%** — Stop immediately. You're damaging domain reputation.

### Spam placement
- **>90% inbox** — Great. Ship more.
- **80-90% inbox** — Acceptable.
- **70-80% inbox** — Yellow. Look at spam-filter-details to see what's triggering.
- **3-5 inboxes as suspicious. Keep it at 2/domain.
- **Aggressive warmup ramp** — Jumping from 5 to 40/day in one week = flag. Ramp over 2-4 weeks.
- **Shared sending IP with spam traffic** — Zapmail/most providers use shared pools. If someone else on your IP spammed, you suffer. Not much to do except wait for pool rotation.

## What to do next

**If any flag fired:** `/deliverability-incident-response` → triage decision tree for whatever was flagged (low reply rate, high bounce, blocked inbox, etc).

**If all clean:** next Monday, run this again. This audit is the Monday task in `/cold-email-weekly-rhythm`.

**Or wait:** if you just applied fixes, wait 7 days then re-audit. Reputation changes propagate slowly.

## Related skills

- `/smartlead-inbox-manager` — execute the action items (rotate, retag, warmup settings)
- `/zapmail-domain-setup-public` — fix DNS/auth issues at the domain provider
- `/spam-word-checker` — check copy for spam-triggering phrases
- `/deliverability-test-public` — lighter-weight SMTP vs Gmail vs Outlook reply/bounce comparison

## Scripts

- `scripts/audit-inboxes.ts` — pull + format inbox inventory
- `scripts/check-domain-auth.ts` — dig-based SPF/DKIM/DMARC checks
- `scripts/audit-performance.ts` — per-inbox sent / replies / bounces / rates from campaign analytics (applies the 1% rule)
- `scripts/run-spam-test.ts` — create + poll + pull Smart Delivery test
- `scripts/generate-report.ts` — synthesize all CSVs into markdown report
- `scripts/_smart-delivery.ts` — shared Smart Delivery API wrapper

## References

- `references/smart-delivery-api.md` — full endpoint reference for Smart Delivery
- `references/dns-records.md` — SPF/DKIM/DMARC record templates + interpretation guide

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [growthenginenowoslawski](https://github.com/growthenginenowoslawski)
- **Source:** [growthenginenowoslawski/coldoutboundskills](https://github.com/growthenginenowoslawski/coldoutboundskills)
- **License:** MIT

Install and usage instructions live in the source repository linked above.