You can have the best copy in the world. If your infrastructure is bad, none of it matters. This is exactly how we set up infrastructure for every new FinalOutreach client.
The components of a healthy sending stack
A modern cold email stack has six layers:
- Sending domains (separate from your primary domain)
- Mailboxes (Google Workspace or Microsoft 365)
- DNS records (SPF, DKIM, DMARC, custom tracking)
- Warm-up tooling (built into Instantly or Smartlead)
- Sending platform (Instantly, Smartlead, or equivalent)
- Monitoring (blacklist + inbox placement)
Skipping any one of them creates a single point of failure that will eventually kill your reply rates.
The build, step by step
Domains
Register 2–3 secondary domains. We use Google Domains or Cloudflare. Pick domains that match your brand closely — finaloutreach.co and getfinaloutreach.com, not random strings. Avoid hyphens. Avoid country TLDs unless you sell into a specific country.
Mailboxes
Buy mailboxes on Google Workspace or Microsoft 365. Avoid third-party SMTP providers — they are flagged at higher rates. Create 3–5 mailboxes per domain. Each mailbox should have a real first name and last name, not "outreach@" or "sales@".
If you need to send 300 emails per day, you need 8–10 mailboxes spread across 2–3 domains. Do the math up front.
DNS records
For every sending domain, configure:
- SPF: list authorized sending IPs.
- DKIM: signing key from Workspace/365.
- DMARC: start with
p=noneandrua=mailto:dmarc@yourdomain. - Custom MX: if you want replies to come back natively.
- Custom tracking domain: subdomain of your sending domain.
Use a DNS validator before sending anything.
Warm-up
Use the warm-up tool built into Instantly or Smartlead. Two-week minimum, four-week recommended. Start at 10–20 emails per day. Increase by 10% daily until you are at 30–40 per day. Never skip warm-up.
Sending platform
Instantly and Smartlead are our defaults. Both spread sending across all mailboxes evenly, manage warm-up, and report inbox placement. Avoid using Mailgun, SendGrid, or Postmark for cold — they are not built for it and carry shared-IP penalties.
Monitoring
Check weekly:
- Blacklists (MxToolbox, Spamhaus)
- Sender score (Validity)
- Inbox placement (GlockApps, MailGenius)
- Bounce rate per mailbox (your sending platform)
Pause any mailbox that drops below 90% inbox placement.
A realistic build timeline
- Day 1–2: Register domains, configure DNS.
- Day 3: Buy mailboxes, configure DKIM.
- Day 4–5: Connect to sending platform, start warm-up.
- Day 6–19: Warm-up runs in the background.
- Day 20: First real campaign at 50 sends per day.
- Day 25: Scale to full daily volume.
Done right, this is 5 business days of active work and 2–3 weeks of waiting. Done wrong, it takes you six months to figure out why your sends are not working.
Common infrastructure mistakes
- Sending from primary domain (kills your transactional email if cold gets flagged).
- Skipping warm-up (every single new domain needs it).
- Using shared tracking domains (they are burned).
- Sending too much per mailbox (Gmail/Outlook flag above ~40/day).
- Ignoring DMARC (most spam landings start here).
What to do in the next 24 hours
- Audit your current sending domain. Is it separate from your primary domain? If not, plan a migration.
- Run a DMARC check on every sending domain. Misconfiguration here is the #1 deliverability killer.
- Confirm every mailbox is below 40 sends/day. If above, add mailboxes — do not push more volume per mailbox.
Done. Your floor is now solid. Now go fix the copy.