OA-1 · Outbound Automation · 100 XP · ~18 min
Why Email Infrastructure Matters
Every email you send passes through a gauntlet of reputation filters before it reaches an inbox. Gmail, Outlook, and every major email provider scores your sending domain on three dimensions:- Authentication — Can they verify you are who you say you are?
- Reputation — Has this domain sent spam before? What’s the bounce rate?
- Engagement — Do people open and reply, or mark it as spam?
The Three Authentication Records
SPF (Sender Policy Framework)
SPF is a DNS record that lists which servers are authorized to send email on behalf of your domain. If an email claims to be fromyou@yourcompany.com but comes from a server not in your SPF record, receiving servers can reject it.
~all is a soft fail — suspicious emails get tagged but not rejected. ~all is recommended over -all (hard fail) for cold outreach domains.
DKIM (DomainKeys Identified Mail)
DKIM adds a cryptographic signature to every email you send. The receiving server checks the signature against a public key in your DNS. If they match, the email is authenticated. DKIM doesn’t prevent spam — it proves the email actually came from you. Combined with DMARC, it creates a strong authentication chain.DMARC (Domain-based Message Authentication, Reporting and Conformance)
DMARC tells receiving servers what to do when an email fails SPF or DKIM:| Policy | Behavior |
|---|---|
p=none | Monitor only — log failures but deliver the email |
p=quarantine | Send failures to spam folder |
p=reject | Reject failures entirely |
p=none to monitor, then move to p=quarantine once you’ve verified your authentication is clean.
Domain Strategy for Cold Outbound
Never use your primary company domain for cold outreach. One spam complaint spike can damage your entire company’s email deliverability — including your transactional and marketing emails. The recommended setup:- Register 2–3 “sending domains” similar to your main domain
- Examples:
yourco.io,getyourco.com,tryyourco.com
- Examples:
- Set up SPF, DKIM, DMARC on each
- Warm each domain separately (see below)
- Rotate sending across domains to stay under per-domain limits
yourcompany.com domain only for replies and transactional email.
Domain Warmup
A brand new domain has zero sending reputation. If you send 500 emails on day one, every major provider will flag it as spam. Warmup is the process of building reputation gradually. Manual warmup schedule:| Week | Daily Volume per Domain |
|---|---|
| Week 1 | 10–20 emails/day |
| Week 2 | 20–40 emails/day |
| Week 3 | 40–75 emails/day |
| Week 4 | 75–150 emails/day |
| Week 5+ | 150–300 emails/day |
Inbox Rotation
Even warmed domains have per-day sending limits before deliverability degrades. The solution is inbox rotation: spread your sends across multiple inboxes and domains. In Instantly, Smartlead, and most modern sequencers, you can add multiple sending accounts and the tool rotates sends automatically. A typical setup:- 3 domains × 2 inboxes per domain = 6 inboxes
- 50 emails/inbox/day × 6 = 300 sends/day total
- Safely under any single domain’s reputation threshold
Audit Checklist
Before running any campaign, run this checklist:- SPF record exists and includes all sending servers
- DKIM record exists and key is active
- DMARC record exists (even
p=noneis fine to start) - Domain is at least 2 weeks old
- Domain has been warmed to your target send volume
- You are not sending from your primary company domain
- Reply-to address is monitored (you’ll get replies)
OA-1 Challenge: Run an MXToolbox Audit (+100 XP)
Run an MXToolbox audit on your sending domain (or a domain you’re setting up). Screenshot the results showing SPF, DKIM, and DMARC status. If any are missing, document what needs to be added.Submit OA-1 Challenge →
Share your MXToolbox audit results and any remediation steps needed. +100 XP on approval.
Next: OA-2 Building Sequences →
Infrastructure is set. Now learn how to architect email sequences that generate pipeline — not just opens.