Inbox Setup

Inbox Setup

Overview

Cold email infrastructure is the foundation underneath every outbound motion. Get it wrong and your copy, targeting, and offer don't matter — you're in spam. This skill covers DIY inbox provisioning across Google Workspace, Microsoft 365, and Azure/Entra, plus DNS authentication, warmup, and infrastructure scaling.

When to Use

• "Set up cold email inboxes"
• "Buy domains for cold outreach"
• "Provision Google Workspace mailboxes"
• "Set up Microsoft 365 for cold email"
• "Configure DNS for sending domains"
• "Scale my sending infrastructure"
• "How many inboxes do I need?"

Authoritative Foundations

• Google Bulk Sender Guidelines — sender authentication, low spam complaint rates, and authenticated alignment are baseline requirements for sustainable outbound. Domain isolation is non-negotiable: never send cold from the primary business domain; use separate sending domains with independent reputation.
• Microsoft Email Sender Guidelines — maintain authenticated mail, clean lists, low complaints, and conservative volume ramps to protect sender reputation.
• Eric Nowoslawski (Growth Engine X) — inbox infrastructure at scale emails/month. Strategy: 2 inboxes per domain, 30 emails/day per inbox, 3-week warmup minimum, keep 50% spare capacity warming at all times.
• Jed Mahrle (Practical Prospecting) — 30,000+ subscribers. "Cold email isn't a numbers game anymore. It's a relevance game. Send fewer emails to better fit accounts."

Prerequisites

• Domain registrar account (Namecheap, GoDaddy, Google Domains)
• Google Workspace or Microsoft 365 tenant (or Azure/Entra for Hypertide-style)
• DNS management access
• Budget: $6-15/mailbox/month for Google, ~$4-6/mailbox/month for Microsoft, plus domain costs ($10-15/domain/year)

Step-by-Step Process

Phase 1: Domain Acquisition

Buy 3-5 secondary domains for cold outreach. Never use your primary business domain.

Rules:

• .com or .co preferred — avoid unusual TLDs that trigger spam filters
• Domain should be a variation that could be a real company (e.g., tryacme.com, getacme.io, acmehq.com)
• Redirect the domain to your main site or a simple landing page
• Set up SSL certificate (Let's Encrypt, free)

Cost: ~$10-15/domain/year. Budget 3-5 domains = $30-75/year.

Phase 2: Mailbox Provider Selection

Eric Nowoslawski Strategy: 2 inboxes per domain, 30 sends/day/inbox, 3-week warmup minimum. Keep 50% spare capacity warming at all times.

Scaling math: To send 1,000 emails/day:

• Google: 1,000 ÷ 25 = 40 inboxes, 20 domains, ~$240-600/mo
• Microsoft: 1,000 ÷ 10 = 100 inboxes, 4 domains, ~$400-600/mo
• Hypertide Entra: 1,000 ÷ 2 = 500 inboxes, 10 orders, ~$500/mo + setup

Phase 3: DNS Authentication (Non-Negotiable)

For every sending domain, configure all three:

SPF: v=spf1 include:_spf.google.com ~all (Google) or v=spf1 include:spf.protection.outlook.com ~all (Microsoft)

DKIM: Generate in admin console (Google: Apps > Gmail > Authenticate email. Microsoft: Security > DKIM). Add the generated TXT record to DNS.

DMARC: Start with v=DMARC1; p=none; rua=mailto:person@example.com. After monitoring for 2-4 weeks, tighten to p=quarantine, eventually p=reject.

Verification: Use MXToolbox or Google Admin Toolbox to verify all records resolve correctly. A single misconfigured record = spam placement.

Phase 4: Warmup (2-4 Weeks Minimum)

• Week 1: 5-10 emails/day to known-engaging addresses
• Week 2: 15-25 emails/day, mix warm and cold
• Week 3: 30-40 emails/day
• Week 4: 40-50 emails/day, full cold sending

Use a dedicated warmup tool (Instantly Warmup, Smartlead Warmup, or Hypertide's built-in warmup). Monitor inbox placement weekly.

Eric Nowoslawski note: "We used to be able to launch low volume without waiting 3 weeks. These days, inboxes may not be ready even after a full 3 weeks." Plan conservatively.

Phase 5: Infrastructure Players

DIY vs Done-For-You: DIY costs less per mailbox but requires 4-8 hours of setup plus ongoing maintenance. Done-for-you (ScaledMail, Hypertide) costs more per mailbox but ships in hours to days. The breakeven: if your time is worth >$100/hr, done-for-you wins at any scale.

Output Format

Infrastructure plan with: domain inventory, mailbox count by provider, DNS record sheet, warmup schedule, cost model (setup + monthly), and monitoring dashboard setup.

Quality Check

• No primary business domain used for cold sending
• SPF, DKIM, DMARC configured and verified on every domain
• 2-3 inboxes per domain maximum (Google) or 25 (Microsoft)
• 30-50 sends/day/inbox maximum
• 2-4 week warmup completed before any cold sends
• 50% spare capacity warming at all times
• MXToolbox or equivalent verification passed on all domains

Common Pitfalls

1. Sending from primary domain. One spam complaint and your password resets, invoices, and support emails go to spam too. Never.

2. Too many inboxes per domain. 10+ mailboxes on one domain signals bulk sending to spam filters. 2-3 for Google, 25 max for Microsoft.

3. Skipping warmup. New domains sent at full volume get blacklisted within 48 hours. There is no shortcut.

4. Sending unverified emails. 5%+ bounce rate triggers automated spam filtering. Always verify with a service like LeadMagic Email Validation before sending.

5. No spare capacity. If inboxes burn out mid-campaign and you have no spares warming, your pipeline stops. Keep 50% spare capacity.

6. DNS misconfiguration. A missing DKIM record or incorrect SPF syntax is caught by every major inbox provider. Triple-check all records.

Execution Artifacts

• references/framework-notes.md — Named frameworks and reference tables
• templates/output-template.md — Deliverable shell for agent output
• scripts/check-output.py — Lightweight deliverable validator
• ../cold-email-strategy/references/eric-nowoslawski-outbound.md — Sending volume strategy, 1:1 backups (Eric Nowoslawski)

Related Skills

• email-deliverability: Full deliverability strategy beyond infrastructure
• domain-infrastructure: DNS auth deep-dive
• sending-platforms: Sequencer selection and setup
• contact-verification: Verify emails before they enter your inboxes