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Deliverability checklist

A cold-email deliverability checklist for the controls you can actually verify.

Review sending identity, mailbox readiness, audience quality, message clarity, capacity, suppression, and monitoring before launch. No checklist can guarantee placement, but it can remove preventable operating mistakes.

Reviewed September 8, 2026 11 minute read Product behavior checked against current implementation
Use this checklist as a launch gate. A failed authentication, suppression, permission, or sender-readiness check should block sending until it is resolved.

1. Establish a verifiable sending identity

  • SPF includes every legitimate service that sends for the domain, in one valid record.
  • DKIM signing is enabled. Test messages validate the signature.
  • DMARC is published, alignment is understood, and reports go to an address the organization controls.
  • The visible From identity is accurate and consistent; headers and subject lines do not imitate replies or misrepresent the sender.
  • Forward and reverse DNS, TLS, and message formatting meet the requirements of the sending and receiving providers.

Review SPF, DKIM, and DMARC in detail →

2. Confirm mailbox readiness

  • The business inbox is connected to its real Google Workspace or Microsoft 365 account.
  • OAuth synchronization and SMTP sending readiness have both been tested; one does not prove the other.
  • The mailbox can receive replies and the reply path points back to the identity recipients see.
  • Recent provider warnings, restrictions, suspicious-login events, and connection failures are resolved.
  • Warmup or ramp activity is visible, bounded, and counted against the mailbox's real capacity.

3. Protect audience quality

  • Every address has a clear, documented reason to be in this campaign.
  • Addresses are verified close enough to send time to make the result useful.
  • Hard bounces, unsubscribes, complaints, and manual blocks are suppressed.
  • The campaign avoids purchased lists and does not keep sending to people who have opted out.
  • The audience and message comply with the rules that apply to the sender and recipient.

4. Make the message recognizable and wanted

  • The sender, subject, and body accurately describe who is writing and why.
  • The message is relevant to the specific recipient segment. Personalization uses real context.
  • Links are visible, understandable, and use domains the sender controls or trusts.
  • The message has a simple way to decline future outreach, and applicable marketing mail supports required unsubscribe behavior.
  • Reply handling and stop-on-reply behavior are tested before the campaign is published.

5. Set capacity below provider ceilings

  • Mailbox limits leave room for normal correspondence and other automated sending.
  • A domain-level limit covers the aggregate activity of every inbox using that domain.
  • Volume begins low, changes gradually, and is spread consistently instead of arriving in bursts.
  • Only connected, send-ready inboxes are eligible for the campaign pool.
  • Warmup and campaign volume share one capacity plan.

See how to choose a safer operating limit →

6. Prepare monitoring and intervention

  • Someone owns provider responses, authentication failures, bounces, complaints, and domain or inbox health.
  • Google Postmaster Tools or the relevant provider diagnostics are configured where volume supports useful reporting.
  • Temporary and permanent SMTP failures remain distinct in reporting and response.
  • The team knows which signals pause one contact, one inbox, one domain, or the entire campaign.
  • Restart criteria are defined before a pause occurs.
Do not use open rate as the launch or pause signal. Google says it does not track open rates and cannot verify third-party open-rate accuracy; privacy features and blocked tracking pixels further weaken that metric.

How MailSequence turns the checklist into controls

MailSequence validates the supported DNS path, tests mailbox readiness, verifies contacts, rechecks suppression at send time, enforces inbox and domain caps, and pauses campaigns when no eligible sender remains. These controls reduce preventable failures; the operator still owns audience selection, message relevance, legal compliance, and the decision to continue.

Primary sources

Turn the checklist into enforceable controls.

Authenticate the domain, connect a real inbox, verify the audience, set conservative limits, and test one campaign.

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