Cold-Email Deliverability

---
name: cold-email-deliverability
description: Use this skill BEFORE launching any cold outbound — it is the infrastructure layer beneath every sequence. Triggers — "my emails are going to spam", "set up a sending domain", "configure SPF DKIM DMARC", "how many emails can I send per day", "warm up a new domain", "why is my bounce rate high", "set up cold email infrastructure", "domain reputation burned", "inbox placement test", "deliverability checklist", "should I send from my main domain", "Google Postmaster Tools". Workflow — buy separate sending domains, authenticate DNS (SPF + DKIM + DMARC), age + warm mailboxes 2-4 weeks, cap per-mailbox volume and scale via mailbox pool, verify every address, keep content plain and clean, then monitor bounce/complaint/placement continuously. Do NOT use for writing the email copy itself — use [[cold-email-craft]]; do NOT use for designing the multi-step cadence — use [[outreach-sequence-designer]]; do NOT use for sizing the list — use [[prospect-list-builder]].
---

# Protect Cold-Email Deliverability

Deliverability is not a copywriting problem; it is an infrastructure and reputation problem. The single most expensive mistake in cold outbound is sending it from your primary corporate domain — one spam-trap hit or complaint spike and your invoices, your hiring emails, and your founder's replies all start landing in spam, and that reputation damage is slow and painful to reverse. Treat cold sending as a blast radius you isolate on purpose: separate domains, separate mailboxes, conservative volume, and relentless monitoring.

The core insight: mailbox providers (Gmail, Outlook) score the *sending identity* — domain + IP + behavioral signals like complaints, bounces, and engagement — not the cleverness of your subject line. You earn primary-inbox placement by behaving like a real human correspondent at low volume, and you keep it by watching the signals that providers actually measure. Good copy on a burned domain still lands in spam.

## When to use this skill

- You are about to launch cold outbound and have not set up dedicated sending infrastructure.
- Reply rates cratered or messages are landing in spam/Promotions and you need to diagnose.
- You are scaling volume and need to size mailboxes, domains, and list to capacity.
- You are configuring DNS authentication and want SPF/DKIM/DMARC done correctly the first time.
- A domain got flagged or blacklisted and you need a recovery plan.

## The workflow

1. **Isolate the blast radius — separate sending domains.** Never send cold from your primary domain (`acme.com`). Register lookalike domains (`trygetacme.com`, `acme-team.com`, `getacme.io`) dedicated to outbound. Redirect them to your main site (301) so they resolve. If one gets burned, you pause and rotate it without touching corporate mail.

2. **Authenticate DNS — all three, or you are getting filtered.**
   - **SPF** (TXT record): authorizes which servers may send for the domain. Publish exactly **one** SPF record; multiple SPF TXT records = a permerror = fail. Stay under the **10 DNS-lookup limit** (each `include:` counts; nested includes count too). Example: `v=spf1 include:_spf.google.com ~all`.