Quick answer

Set up SPF and DKIM correctly, publish a DMARC policy, use a consistent From domain, honour unsubscribe requests quickly and monitor complaint and bounce signals. Authentication alone cannot rescue unwanted or poorly targeted email.

Start with a clean permission-based list and a sending process the team can maintain.

What I would check first

Verify that the sending domain aligns with the visible From address, authentication passes, DNS records are valid, marketing messages include one-click unsubscribe and suppression lists are respected.

Review hard bounces, spam complaints, inactive subscribers, sudden volume changes and whether multiple tools are sending from the same domain without coordination.

Decision framework

Separate transactional and marketing sending where practical, choose a clear sender identity and decide how inactive subscribers will be suppressed or re-engaged. The right policy is the one the business can monitor and enforce.

For list growth, prefer clear consent and a specific subscriber promise over broad collection tactics that create low engagement.

Implementation steps

Publish SPF, DKIM and DMARC records with the email provider, test alignment, configure unsubscribe and preference controls, create bounce and complaint workflows and establish a regular list-health review.

Google’s current sender guidance says unauthenticated mail may be rejected or spam-foldered and identifies SPF, DKIM, valid DNS, TLS, DMARC and one-click unsubscribe as important requirements for relevant senders. citeturn580680search2turn580680search3

Common mistakes

Avoid buying lists, sending to old inactive contacts without a plan, changing domains during a deliverability problem, ignoring complaints or measuring success only by opens.

Do not make sudden volume jumps without considering subscriber expectation, engagement and provider limits.

Measurement and business implications

Track delivery, bounce, complaint, unsubscribe, click, conversion and revenue or lead outcomes by segment. Keep an eye on list growth quality, not just size.

Pair this guide with the email beginner guide, content strategy guide and UTM tools so deliverability supports a measurable customer journey.