In short
- Authenticate the domain: SPF, DKIM, DMARC.
- Keep the list clean and permission-based.
- Warm up and hold a steady cadence.
- Prune unengaged contacts rather than hoarding them.
Foundation: authentication
SPF says which servers may send for your domain, DKIM cryptographically signs your mail, and DMARC tells receivers what to do when neither aligns. All three should be published before you send volume.
Hygiene: the list
- Collect addresses with explicit permission; double opt-in where practical.
- Validate syntax and deduplicate on every import.
- Suppress hard bounces permanently.
- Honour unsubscribes immediately and visibly.
Pattern: warm-up and cadence
Increase volume gradually on a new domain or IP, and then keep it predictable. Receivers reward consistency. A domain that sends 5,000 a week steadily is in a stronger position than one that sends 20,000 once a quarter.
Engagement: the part nobody wants to hear
Engagement is now a primary signal. Sending to people who never open costs you placement with the people who do. Segment by engagement and mail your inactive segment rarely — or remove it.
Structure: the message itself
- HTML plus a genuine plain-text alternative.
- A stable, recognisable From name and address.
- A working reply address that a human reads.
- Unsubscribe headers and one-click unsubscribe.
- Links on your own domain rather than shorteners.
Monitoring
Watch bounce reasons by receiving domain, complaint signals, and DMARC reports. Deliverability degrades gradually; monitoring is how you notice before a campaign fails.
Checklist
- SPF, DKIM, and DMARC published and aligned.
- Permission-based, validated, deduplicated list.
- Gradual warm-up and steady cadence.
- Engagement segmentation in place.
- Plain-text, unsubscribe headers, real reply address.
- Bounce and DMARC reports reviewed regularly.
Run these checks now
Questions people ask
What is a good bounce rate?
Lower is always better; sustained hard bounces above a couple of percent indicate a list-quality problem worth fixing before your next send.
Does a dedicated IP improve deliverability?
Only at consistent volume. A dedicated IP with irregular low volume can perform worse than well-managed shared infrastructure, because it never builds a stable reputation.
How long until improvements show?
DNS and content fixes can show within days. Reputation and engagement improvements take weeks of consistent sending.