Cold Infrastructure Setup (n8n + Smartlead + Apollo)

Why You Need Dedicated Cold Outreach Infrastructure

If you’re sending cold emails from your primary domain — the same one your team uses for customer support, investor updates, and partner communications — you’re one spam report away from destroying your deliverability for everything.

This guide walks you through setting up a proper cold outbound infrastructure stack using secondary domains, properly configured DNS, and an automated enrichment pipeline. Total setup time: ~4 hours. Monthly cost: ~$150–200.

The Stack

Layer	Tool	Purpose	Cost
Sending	Smartlead	Multi-inbox cold email sequencing	~$94/mo
Enrichment	Apollo.io	Contact finding + email verification	~$49/mo (free tier available)
Automation	n8n (self-hosted)	Workflow orchestration between tools	Free (self-hosted)
DNS/Domains	Namecheap / Cloudflare	Secondary sending domains	~$10–12/domain/year
Email Hosting	Google Workspace	Sending inboxes on secondary domains	~$7/inbox/mo

Step 1: Secondary Domain Setup

Buy 2–3 Secondary Domains

Your secondary domains should look related to your primary but be clearly separate. Pattern:

Primary Domain	Good Secondaries	Bad Secondaries
acmelabs.com	acmelabs.io, getacmelabs.com	totallyunrelated.com
deeptech.ai	deeptech.co, trydeeeptech.com	randomname123.xyz

Where to buy: Namecheap or Cloudflare Registrar (cheapest renewals).

Rules:

No hyphens in domain names
Stick to .com, .io, .co TLDs
Don’t use .xyz, .info, or other spam-associated TLDs

Set Up Email Hosting

Create 2–3 Google Workspace inboxes per secondary domain:

laksh@acmelabs.io
l.pujary@acmelabs.io
laksh@getacmelabs.com

Why multiple inboxes? Smartlead rotates across inboxes to spread sending volume and improve deliverability.

Step 2: DNS Authentication (SPF, DKIM, DMARC)

This is the most critical step. Without proper DNS records, your emails go straight to spam.

SPF Record

Add a TXT record to each secondary domain:

Host: @
Type: TXT
Value: v=spf1 include:_spf.google.com ~all

What it does: Tells receiving email servers “Google Workspace is authorized to send email on behalf of this domain.”

DKIM Record

In Google Workspace Admin → Apps → Gmail → Authenticate Email:

Generate a DKIM key for your domain
Add the provided TXT record to your DNS
Start authentication in Google Workspace

Host: google._domainkey
Type: TXT
Value: v=DKIM1; k=rsa; p=[your-public-key]

DMARC Record

Host: _dmarc
Type: TXT
Value: v=DMARC1; p=none; rua=mailto:dmarc@acmelabs.io

Start with p=none (monitoring mode). After 2–4 weeks of clean sending, upgrade to p=quarantine.

Verification

Use MXToolbox to verify all three records are properly configured:

SPF: mxtoolbox.com/spf.aspx
DKIM: mxtoolbox.com/dkim.aspx
DMARC: mxtoolbox.com/dmarc.aspx

Step 3: Domain Warming

Do not start sending cold emails on Day 1. New domains have zero reputation. You need to warm them.

Automated Warming with Smartlead

Smartlead has built-in domain warming:

Connect your secondary domain inboxes to Smartlead
Enable auto-warming on each inbox
Set warming volume: start at 5 emails/day, ramp to 30 over 3 weeks
Warming emails are sent to Smartlead’s warming network — real inboxes that open, reply, and mark as “not spam”

Warming Timeline

Week	Daily Volume	Action
1	5/inbox	Warming only, no cold sends
2	15/inbox	Warming only, no cold sends
3	25/inbox	Begin sending 5–10 cold emails/day alongside warming
4+	30/inbox	Full cold sending at 15–25/inbox/day + ongoing warming

Critical: Never exceed 30 cold emails per inbox per day. Ever. This is the hard ceiling for sustained deliverability.

Step 4: Apollo.io Lead Enrichment Pipeline

Building Your ICP (Ideal Customer Profile) in Apollo

Set up a Saved Search with these filters:

Company:
  - Industry: [your target vertical]
  - Employee count: 50–5,000 (enterprise but reachable)
  - Revenue: $10M–$500M
  - Technologies: [relevant tech stack signals]

Contact:
  - Title: VP, Director, Head of [relevant department]
  - Seniority: VP, Director
  - Department: Engineering, Operations, R&D, [your buyer's dept]
  - Location: United States

Export and Verify

Select up to 25 contacts per export batch
Use Apollo’s built-in email verification (green = verified, yellow = risky, red = skip)
Export only verified emails as CSV

Data Fields to Export

First Name, Last Name, Title, Company, Email (verified),
LinkedIn URL, Company Revenue, Employee Count, Industry

Step 5: n8n Automation Workflows

Workflow 1: Apollo → Smartlead Pipeline

This workflow automatically moves verified leads from Apollo into Smartlead campaigns.

Trigger: Webhook (or Cron — every 6 hours)
    ↓
Apollo API: Fetch new contacts from saved search
    ↓
Filter: Only verified emails, not already in Smartlead
    ↓
Enrich: Pull LinkedIn headline, recent posts (optional)
    ↓
Smartlead API: Add to campaign with personalization fields
    ↓
Google Sheets: Log lead to tracking sheet

Workflow 2: Smartlead Reply → Notification

When someone replies to a cold email, you want to know immediately.

Trigger: Smartlead Webhook (reply received)
    ↓
Filter: Positive/Interested replies only
    ↓
Slack/Email: Send notification with reply content
    ↓
Google Sheets: Update lead status to "Replied"

Workflow 3: Weekly Campaign Health Check

Trigger: Cron (every Monday 9am)
    ↓
Smartlead API: Pull campaign stats
    ↓
Calculate: Open rate, reply rate, bounce rate
    ↓
Filter: Flag campaigns with bounce rate > 3%
    ↓
Slack: Weekly summary with action items

Deliverability Monitoring Checklist

Run this weekly:

Metric	Healthy	Action if Unhealthy
Open rate	> 45%	Check subject lines, warming status
Reply rate	> 2%	Improve copy, tighten targeting
Bounce rate	< 2%	Re-verify list, check domain health
Spam rate	< 0.1%	Reduce volume, improve content
Warming score	> 90%	Keep warming enabled, don’t increase volume

Common Mistakes

Sending from primary domain — Destroys deliverability for your entire company
Skipping the warming period — New domains without reputation get flagged instantly
Too many emails per inbox — 30/day is the max. Period.
Not verifying emails before sending — Bounces kill your domain reputation
Including links and images in first email — Triggers spam filters. Text-only for cold emails.
Using the same copy across hundreds of sends — Spam filters detect templates. Add personalization.

Monthly Cost Breakdown

Item	Monthly Cost
Smartlead (Pro)	$94
Apollo.io (Basic)	$49
n8n (self-hosted on $6 VPS)	$6
3 secondary domains	~$3 (amortized)
Google Workspace (3 inboxes × 2 domains)	~$42
Total	~$194/mo

For a technical founder doing SBIR commercialization, this infrastructure supports outreach to 50–75 qualified prospects per week — more than enough to fill your discovery call pipeline.

This guide is part of the Phase II Commercialization Vault — free resources for SBIR/STTR founders navigating the path from Phase I to commercial traction.