email-infra-guide-md.md
Cold Email Infrastructure
Complete guide to setting up and maintaining cold email sending infrastructure — from zero to live campaigns.
The Redline (Follow In Order)
- Calculate infrastructure needs
- Acquire secondary domains
- Create workspaces & mailboxes
- Configure DNS (SPF, DKIM, DMARC)
- Connect to sending platform (Instantly)
- Warm up mailboxes (2–3 weeks minimum)
- Go live with conservative limits
- Monitor and maintain ongoing
For detailed walkthroughs of each step, see email-infra-step-by-step.md. For DNS issues and deliverability problems, see email-infra-troubleshooting.md.
Critical Rules (Never Break These)
- Never use a primary domain for cold outreach. Always use secondary domains.
- Maximum 2 mailboxes per domain. Limits blast radius if a domain gets burned.
- One domain = one workspace/tenant. Never add multiple domains to one Google Workspace or Microsoft 365 account.
- Use multiple registrars. No single point of failure.
- Warm up for 2–3 weeks minimum before sending any campaigns.
- Never disable warm-up once campaigns are running.
- Start conservative, scale gradually. Easier to add capacity than recover from deliverability damage.
Infrastructure Sizing
Core Formula
Work backwards: Monthly goal → Daily volume → Mailboxes → Domains
Send Limits Per Provider
| Provider | Safe Daily Limit per Mailbox |
|---|---|
| Google Workspace | 15–25 emails/day |
| Microsoft 365 | 10–15 emails/day |
Sizing Calculator
| Monthly Goal | Daily Volume | Mailboxes Needed (with 50% buffer) | Domains Needed |
|---|---|---|---|
| 3,000 | 150 | 10–12 | 5–6 |
| 7,500 | 375 | 18–23 | 9–12 |
| 15,000 | 750 | 38–45 | 19–23 |
| 30,000 | 1,500 | 75–90 | 38–45 |
Sizing Steps
- Define monthly email goal
- Divide by 20 working days = daily volume
- Divide daily volume by 20 (conservative) or 25 (aggressive) = mailboxes
- Multiply by 1.5 = mailboxes with buffer
- Divide mailboxes by 2 = domains needed
Provider Split
| Provider | Allocation | Why |
|---|---|---|
| Google Workspace | 60% | Higher send limits, good deliverability |
| Microsoft 365 | 40% | Different infrastructure, risk diversification |
Practical minimum: 15 mailboxes (~375 emails/day capacity).
Domain Acquisition
Naming Patterns (Good)
For primary domain acme.com:
- acmehq.com, getacme.com, tryacme.com, goacme.com
- teamacme.com, hiacme.com, meetacme.com, acmeco.com
Naming Patterns (Bad)
- Random strings, misspellings, spammy words (deals, offers)
- Numbers, excessive hyphens
TLD Rules
- .com is king — best deliverability and trust
- .org acceptable as secondary
- Avoid .io, .ai, .co for cold email
Recommended Registrars
Spread purchases across multiple:
- Cloudflare — no markup, great DNS management
- Namecheap — affordable, good for bulk
- GoDaddy — widely used
- Squarespace (ex–Google Domains) — reliable
- Porkbun — cheap, good reputation
Per-Domain Checklist
- Domain registered
- Auto-renew enabled
- Whois privacy enabled
- Logged in tracking spreadsheet
Workspace & Mailbox Setup
Google Workspace (~$6/user/month, Business Starter)
- Create new workspace at workspace.google.com
- Add secondary domain → verify ownership via TXT record
- Create mailboxes (max 2 per domain, real names)
- DNS records configured during this step (see DNS section)
Microsoft 365 (~$6/user/month, Business Basic)
- Purchase plan at microsoft.com/microsoft-365/business
- Add secondary domain → verify ownership via TXT record
- Create mailboxes (max 2 per domain, real names)
- Critical: Enable SMTP & IMAP in Admin Center → Users → Active Users → Mail → Manage email apps
- Wait 1 hour after enabling SMTP before connecting to Instantly
Mailbox Naming
Good: Real first names — alex@, sarah@, michael@, james@, emma@, david@ Bad: sales@, info@, noreply@, hello@, outreach@
Pro tip: Keep names consistent across domains (alex@ on all your domains).
Profile Pictures
Add a professional headshot to every mailbox. This improves deliverability and reply rates. Do not skip.
DNS Configuration
Every domain needs all four records. Missing one can tank deliverability.
| Record | Purpose |
|---|---|
| MX | Routes incoming email to your provider |
| SPF | Declares which servers can send for your domain |
| DKIM | Digital signature proving email authenticity |
| DMARC | Policy for handling SPF/DKIM failures |
SPF Records
- Google:
v=spf1 include:_spf.google.com ~all - Microsoft:
v=spf1 include:spf.protection.outlook.com ~all - Only ONE SPF record per domain (most common mistake)
DMARC Record
| Field | Value |
|---|---|
| Type | TXT |
| Host | _dmarc |
| Value | v=DMARC1;p=none;sp=none;pct=100;rua=mailto:you@domain.com;ri=86400;aspf=r;adkim=r;fo=1 |
Domain Forwarding
Redirect secondary domains → main website (301 permanent redirect). Makes domains look legitimate when prospects check.
Custom Tracking Domain (Recommended)
CNAME record: inst → prox.itrackly.com (TTL 300)
Then configure in Instantly → Settings → Custom Tracking Domain.
Cloudflare users: proxy must be OFF (grey cloud).
Testing DNS
- Instantly: Email Accounts → Test domain setup (easiest)
- MXToolbox: mxtoolbox.com — MX, SPF, DMARC, blacklist
- Mail-Tester: mail-tester.com — deliverability score (aim 8+/10)
- Google Postmaster Tools: postmaster.google.com — Gmail reputation
For DNS troubleshooting, see troubleshooting.md.
Connecting to Instantly
Google Accounts (OAuth — Recommended)
- Email Accounts → Add New → Google → OAuth
- Copy Client ID → Google Workspace Admin → Security → API Controls → Manage App Access
- Configure new app → paste Client ID → select "Instantly OAuth Email v1"
- Scope: All users, Access: Trusted
- Return to Instantly → Login to complete
Microsoft Accounts (One-by-One Only)
- Email Accounts → Add New → Microsoft
- Confirm SMTP is enabled → sign in
- Check "Consent on behalf of your organization"
- Accept permissions
Microsoft cannot be bulk imported. Plan time accordingly.
Post-Connection Settings
- Daily send limits: Google 15–25, Microsoft 10–15
- Custom tracking domain: Enable per account
- Account tags: Organize by client / domain / provider
- Slow ramp: Enable — starts at 2/day, increases by 2/day
Warm-Up
Timeline
| Period | What Happens | Can Send Campaigns? |
|---|---|---|
| Week 1 | Foundation — low volume warm-up starts | No |
| Week 2 | Building — volume increases, health scores appear | No |
| Week 3 | Ready — health scores 70%+ (ideally 90%+) | Yes, conservatively |
Minimum: 2 weeks. Recommended: 3 weeks.
Recommended Warm-Up Settings
| Setting | Value |
|---|---|
| Daily warmup limit | 10–15 |
| Reply rate | 30–40% |
| Increase by day | Enabled |
| Read emulation | Enabled |
| Open rate | 80–90% |
| Spam protection | 100% |
| Mark important | 30–50% |
Warm-Up Pools
| Pool | Flame Color | Quality |
|---|---|---|
| Premium | Blue | Best — aged Google/Outlook accounts |
| Standard | Green | Good — default for all accounts |
| Basic | Orange | Lower — mostly SMTP |
| Disabled | Red | Needs reactivation (DNS issue likely) |
Red Flame Recovery
- Fix DNS (run "Test domain setup" in Instantly)
- Click red flame → Request Reactivation Code
- Check inbox for code → enter in Instantly
Going Live
Ramp Schedule
| Provider | Week 1 | Week 2–3 | Week 4+ |
|---|---|---|---|
| 10–15/day | 15–20/day | 20–25/day | |
| Microsoft | 5–10/day | 10–12/day | 12–15/day |
Deliverability Settings (Instantly)
- Text-only first email — reduces spam filter triggers
- Disable open tracking — improves inbox placement (Frontal default)
- ESP matching — Google sends to Gmail, Microsoft sends to Outlook
- Limit emails per company — 2–3 per company per day (workspace-wide)
- Slow ramp — enable for new accounts only
First Campaign
- Start with 50–100 leads
- Monitor 2–3 days before scaling
- Scale by adding mailboxes, not pushing limits higher
Healthy Metrics
| Metric | Healthy | Warning | Stop |
|---|---|---|---|
| Open rate | 50%+ | 30–50% | Below 30% |
| Reply rate | 2%+ | 1–2% | Below 1% |
| Bounce rate | Below 3% | 3–5% | Above 5% |
| Spam complaints | 0 | Any | Multiple |
Ongoing Monitoring
Daily (5 min)
- Check bounce rates (<5%), reply rates, spam complaints
- Spot-check 2–3 warm-up emails
- Watch for blacklist alerts
Weekly (15 min)
- Google Postmaster Tools + Microsoft SNDS
- MXToolbox blacklist check
- Compare week-over-week trends
Monthly (30 min)
- Update suppression list, audit bounces
- Review domain reputation, clean old leads
- Rotate warm-up email content
Quarterly (1 hour)
- Full DNS audit across all domains
- Infrastructure cost review
- Strategic capacity planning
Scaling Rule
- Increase volume by max 20% per week
- Add new domains instead of pushing existing ones
- Stagger new domain launches (1 per week max)
- New domains go through full warm-up cycle
For detailed recovery protocols, see email-infra-troubleshooting.md.
Infrastructure Tracking Spreadsheet
Maintain a spreadsheet with:
| Domain | Registrar | Provider | Mailbox 1 | Mailbox 2 | Admin Email | Status |
|---|---|---|---|---|---|---|
| acmehq.com | Cloudflare | alex@acmehq.com | sarah@acmehq.com | admin@you.com | Active | |
| getacme.com | Namecheap | Microsoft | alex@getacme.com | sarah@getacme.com | admin@you.com | Warming |
Track: domain, registrar, provider, mailboxes, admin email, warm-up status, health score.
Seasonal Expectations
| Period | Expected Impact |
|---|---|
| December holidays | 20–30% engagement drop, recovers mid-January |
| July–August | 10–20% drop (vacation season) |
| End of quarter | Lower response rates (prospects closing deals) |
| Industry conferences | 15–25% drop during event week |
Don't panic during seasonal dips. Investigate only if the drop exceeds norms or doesn't recover.
Built by Frontal & Ivan Falco. For questions on implementation or anything not covered here, reach out to Ivan directly on LinkedIn.