cold-email-deliverability

name	cold-email-deliverability
description	15-point pre-campaign domain health check across DNS (SPF, DKIM, DMARC, MX, BIMI), reputation (SNDS, Postmaster, blacklists), warm-up status (mailbox age, send volume ramp, reply ratio), and content (spam-trigger lint, link-to-text ratio, image-to-text ratio). Returns a 0-100 deliverability score and a fix-order. Uses native DNS lookups + public blacklist APIs — no paid tools required. Loaded by the main cold-email skill when the user asks about deliverability, domain health, SPF/DKIM/DMARC, or pre-launch readiness.
user-invocable	false
allowed-tools	["Read","Write","Bash","WebFetch"]

Cold Email Deliverability — 15-point pre-campaign domain health

Loaded by cold-email when the user asks about deliverability, SPF/DKIM/DMARC, domain health, or "are we ready to send."

Activation triggers

• "Check deliverability"
• "Domain health"
• "SPF / DKIM / DMARC"
• "Are we ready to send"
• "Pre-campaign check"
• "Why are we landing in spam"
• "Inbox placement"

Workflow

1. Inputs

Ask for:

• sending_domain — e.g. outreach.jmc.com
• from_address — full address used in the From: header
• inbox_provider — GSuite / O365 / Smartlead / Instantly / custom
• mailbox_age_days — how long this address has been sending
• current_daily_send_volume — emails/day
• recent_reply_ratio — % over the last 14 days (skip if first campaign)

2. Run the 15 checks

The 15 checks span four categories:

#	Category	Check	How
1	DNS	SPF record exists	dig TXT <domain> for v=spf1
2	DNS	SPF includes inbox provider	Lookup includes match provider
3	DNS	SPF lookup count ≤10	Resolve all includes recursively
4	DNS	DKIM selector resolves	dig TXT <selector>._domainkey.<domain>
5	DNS	DKIM key ≥1024 bits	Decode the p= value
6	DNS	DMARC record exists	dig TXT _dmarc.<domain>
7	DNS	DMARC policy ≠ none for cold outreach	p=quarantine or p=reject required for bulk senders post-Feb 2024
8	DNS	DMARC has rua= reporting	Aggregate report URI configured
9	Reputation	Domain not on Spamhaus / SURBL	Lookup against public blacklist APIs
10	Reputation	rDNS / PTR record matches sending IP	dig -x <sending-ip> matches forward
11	Warm-up	Mailbox age ≥21 days	Compare mailbox_age_days to threshold
12	Warm-up	Daily send ramp ≤30/day for first 14 days	Compare current_daily_send_volume
13	Warm-up	Reply ratio ≥3% over 14 days	(Hard threshold for B2B cold)
14	Content	TLS support on MX	Confirm STARTTLS advertised
15	Content	DKIM signs the body, not just headers	Test message via test tool (mxtoolbox)

3. Run the lookups

Use Bash for dig, host, nslookup. Use WebFetch for blacklist lookups against public APIs (Spamhaus DBL, MultiRBL.valli.org).

Never call paid APIs. Never ask for an API key. If a check requires a tool the user doesn't have, fall back to telling the user the manual lookup command + expected output.

Example fallback:

Check 9 (Spamhaus / SURBL) requires multirbl.valli.org or mxtoolbox.com — copy-paste this URL: https://multirbl.valli.org/lookup/<sending-domain>.html Look for any red flags in the response.

4. Score

Each of the 15 checks is binary (pass / fail). Score:

Deliverability = (passingChecks / 15) * 100

5. Output the fix-order

Failing checks get ranked by:

1. Fail-blocker severity: SPF / DKIM / DMARC failures and blacklist hits are blockers — fix BEFORE sending anything.
2. Compounding impact: a DNS fix compounds across all campaigns forever.
3. Ease: TXT record changes are 1 hour; warm-up is days.

Output:

# Deliverability check — <domain>

## Score: <0-100>/100 — <grade>

| # | Check | Status |
|---|---|---|
| 1 | SPF record | ✓ / ✗ |
| 2 | SPF includes provider | ✓ / ✗ |
... (all 15) ...

## Fix order

### CRITICAL (do not send until fixed)
- Check N: <description> — <fix>

### IMPORTANT (fix in next 7 days)
- ...

### NICE-TO-HAVE
- ...

Grade thresholds

Score	Grade	Verdict
95-100	A	Ready. Ship.
85-94	B	Ship but fix the B-list within 30 days
70-84	C	Don't scale spend. Fix top 3 first.
50-69	D	Hold campaign. Fix critical-tier items.
0-49	F	Pause everything. Rebuild infra.

References

• The Pre-Campaign Domain Health Checklist (15-point PDF) ships in Operator Pass.
• DMARC + Feb-2024 bulk-sender rules (Google / Yahoo / Microsoft) — see ../../cold-email/references/bulk-sender-rules.md.
• The full Cold Email & Outreach Craft course covers deliverability forensics in 4 lessons: jaymountconsulting.com/learn/courses/cold-email-outreach-craft