Email Deliverability Checklist
Work through every phase in order: domain authentication, list hygiene, warmup, sending behavior, placement testing, and ongoing monitoring. Skip a phase and the later ones cannot compensate.
TL;DR
6 phases: the order that determines whether emails land
Most deliverability failures trace back to three skipped steps: authentication not completed before connecting to a sending platform, lists uploaded without verification, or new inboxes sent at full volume before warmup. Each phase below assumes the previous one is complete.
6 phases from domain auth to ongoing monitoring, with tool fit recommendations per phase based on verified data only.
The Full Checklist
Six-phase deliverability checklist at a glance
| Phase | What to check | Gate before moving on | Priority |
|---|---|---|---|
| 1. Domain setup | SPF valid · DKIM matched · DMARC set · Dedicated sending domains registered | All DNS records pass a live authentication check before any inbox is connected | Critical: do first |
| 2. List hygiene | All contacts verified externally · Catch-alls separated · Hard bounces suppressed | Verified list file in hand before any contacts are uploaded | Critical: before every upload |
| 3. Warmup | Warmup enabled on every new inbox · Domain at least 14 days old · Warmup running minimum 2 weeks before first campaign | Warmup start date logged · At least 14 domain-age days confirmed | High: before first send |
| 4. Sending behavior | Daily send cap set per inbox · Randomized intervals active · Inbox rotation configured · Global block list active | Per-inbox daily limit set explicitly, not relying on platform default | High: before scaling |
| 5. Placement testing | Placement test on actual campaign template · Gmail and Outlook scores above 85% · Content analysis clean | Placement score confirmed above threshold before campaign goes to full volume | Medium: before new domains go live |
| 6. Monitoring | Bounce threshold alert at 2% · Blacklist monitoring active · Spam placement alerts enabled · Weekly review set | At least one automated alert active per sending domain | Ongoing: never complete |
Phase 1 + 2
Authentication + list hygiene: skip either and warmup cannot save you
SPF, DKIM, and DMARC must all be in DNS before any inbox connects to a sending platform. SPF authorizes sending servers, DKIM signs each email cryptographically, DMARC tells receivers what to do on failure. Use dedicated secondary domains (getcompanyname.com) for outbound, registered at least 14 days before launch.
A bounce rate above 2% on the first send from a new inbox can permanently damage domain reputation before warmup offsets it. Verify every list before upload and send to catch-all addresses from a dedicated cluster capped at 20 emails/day until you have bounce data on that segment.
Phase 3 + 4
Warmup: 14 domain days minimum, 20 emails/day cap in month one
Platform-native warmup (Instantly, Smartlead, Woodpecker) handles the core function once enabled. The threshold is 14 domain-age days plus 2 warmup-active weeks before the first campaign, regardless of platform.
Cap new inboxes at 20-30 emails/day in month one and increase by 10-15 per week while bounce rates stay below 2%. Set per-inbox limits explicitly in the platform rather than relying on defaults.
Distributing 100 daily emails across 4-5 inboxes at 20-25 each lowers per-inbox reputation exposure and raises total send capacity without overloading any single sender.
Phase 5 + 6
Placement testing below 85%: catch inbox failures before full volume
Reply rate does not confirm inbox placement. Run a test on the actual campaign template before any new domain scales, and pause if Gmail or Outlook placement falls below 85%.
Minimum monitoring setup: a bounce threshold alert at 2%, blacklist monitoring per domain, and a real-time spam placement alert per active inbox. Folderly Pulse (free) delivers Slack alerts; GlockApps monitors 50+ blacklists with automated notifications.
When a domain appears on Spamhaus or Barracuda, inbox placement drops to near zero for affected recipients. Pause all campaigns on the listed domain, identify the cause, remediate, and request removal before resuming sends.
Recommended Tools
7 tools mapped to the 6 phases
No single tool covers all six phases. Match tools to phases using the list below.
Common Questions
FAQ: warmup timing, bounce thresholds, DMARC setup
Always in sequence: authentication before warmup, warmup before first send, list verification before upload, placement testing before scaling. Phases 5 and 6 run in parallel with active campaigns.
Minimum two weeks of active warmup on a domain at least 14 days old. Most teams run 3-4 weeks before full-volume outbound on a brand-new domain.
Set a hard auto-pause at 2% hard bounce rate per send batch in your sending platform. Any batch hitting 1% should prompt a list source audit before the next send.
Platform-native warmup (Instantly, Smartlead, Woodpecker) covers the core function for most teams. Add an external tool only if placement tests show degrading inbox rates.
Start with p=none to collect failure reports without affecting delivery. Move to p=quarantine after 2-4 weeks of clean data, then p=reject only when all senders are fully authenticated.
Checklist complete. Now find the right verification tool.
Compare the best email verification tools by accuracy, catch-all handling, credit pricing, and fit for cold email workflows.