Pass five gates before sending: the audience belongs, the identity is truthful, authentication is aligned, volume is conservative, and every negative signal can stop future mail. If any gate is unobservable, the campaign is not ready.
1. Audience and message gate
No DNS record can rescue an irrelevant list. The FTC’s U.S. guidance also makes clear that accurate identity, non-deceptive subjects, location, opt-out, and vendor oversight are substantive obligations, not copy polish. [3]
- Every segment has a documented business reason to receive this specific message.
- Exclusions cover competitors, existing customers, prior opt-outs, complainers, invalid addresses, and unsuitable roles.
- Claims are supportable from current evidence and do not imply a relationship that does not exist.
- The From name, Reply-To, subject, and routing identity are accurate.
- The message includes the required sender identification, postal address, and opt-out mechanism for the applicable program.
2. Technical identity gate
Google requires SPF or DKIM for all senders to Gmail and adds SPF, DKIM, DMARC, alignment, DNS, and unsubscribe requirements for bulk senders. Its guidance recommends authentication for every domain rather than treating the threshold as a target. [1][2]
- One current SPF record authorizes every legitimate sending path without obsolete includes.
- DKIM signs with the intended domain and a sufficiently strong key.
- DMARC is published, reports are monitored, and the visible From domain aligns through SPF or DKIM.
- Forward DNS and PTR/reverse DNS are valid for direct-send infrastructure.
- TLS is used and messages conform to Internet message format.
- MX and role mailboxes can receive replies, abuse reports, and DMARC reports.
3. Volume and queue gate
Google advises senders to increase volume slowly, avoid bursts, monitor server responses and reputation, and reduce volume when bounces or deferrals rise. A daily quota without queue feedback is not sufficient control. [1]
- New identities begin with low, consistent, legitimate traffic.
- Limits exist per mailbox, domain, sending IP, campaign, and receiving MX.
- Temporary deferrals slow the affected path instead of creating faster retries.
- Queue depth, oldest-message age, throughput, and retry reasons are observable.
- A global hold stops submission while preserving state for investigation.
4. Recipient-signal gate
- Any reply stops the active automated sequence before classification.
- Hard bounces suppress the address immediately.
- Spam complaints create an auditable global suppression.
- One-click and visible unsubscribe paths agree on the same suppression state.
- Webhook retries and duplicate events are idempotent.
- No later import can silently reactivate a suppressed recipient.
5. Daily operating gate
Review negative replies, permanent failures, temporary deferrals, complaint signals, queue anomalies, domain authentication, blocklist observations, and sending volume by receiving network. Look at absolute counts and rates with denominators.
Pause when the evidence is unclear. Deliverability vendors cannot guarantee inbox placement, and a seed test does not reproduce each recipient’s filtering context. The goal is controlled, recipient-respecting operation—not a screenshot showing 100 percent inbox placement.
Common questions
Questions, answered plainly
What is the most important deliverability factor?
There is no single factor, but audience relevance and recipient response sit upstream of most technical outcomes. Authentication and operational controls are still mandatory.
Does SPF, DKIM, and DMARC guarantee inbox placement?
No. They establish authorization and alignment signals; mailbox providers still evaluate reputation, content, behavior, and recipient feedback.
What should stop a campaign automatically?
Replies, opt-outs, hard bounces, complaints, provider blocks, broken authentication, and unsafe queue or rate conditions should all have deterministic stop paths.
Evidence
Sources and methodology
Product capabilities were checked against first-party documentation available on September 9, 2026. Policies, plans, and prices can change; verify them before buying. General guidance is educational and is not legal advice.
- Email sender guidelines Google. Authentication, DNS, spam-rate, formatting, unsubscribe, and volume guidance for Gmail.
- Email sender guidelines FAQ Google. Bulk-sender definitions and DMARC alignment details.
- CAN-SPAM Act: A Compliance Guide for Business U.S. Federal Trade Commission. Official U.S. guidance for commercial email, including B2B messages.
- DMARC overview DMARC.org. How DMARC builds on SPF and DKIM to add alignment, policy, and reporting.
Your agent can do the thinking.
The infrastructure still needs a grown-up.