Email Deliverability Checklist: 12 Checks Before Your Next Campaign

Authentication: the non-negotiables

Before any campaign, confirm SPF, DKIM and DMARC are all published and valid for your sending domain. A single typo in a DNS record can silently break authentication for every email you send.

Also confirm you are sending from a domain you own, not a free mailbox. Free-mail senders are filtered harder, and they cannot build a reputation you control.

List hygiene: clean before you send

Remove hard bounces from your last campaign, and suppress addresses that have not opened anything in months. A smaller, engaged list beats a large, dead one — for deliverability and for results.

Never buy lists. Purchased lists are full of stale addresses and spam traps, and one trap can damage your domain's reputation for weeks.

Content and volume: look human

Avoid heavy images with little text, URL shorteners, and spam-trigger phrases in your first lines. Plain, relevant copy with one clear link performs better and filters less.

Keep daily volume steady and ramp new domains slowly. If your campaign is much larger than your usual sending, split it across days rather than blasting it at once.

After you send

Watch bounces and spam complaints, not just opens. A rising bounce rate is an early warning — pause, clean the list, and fix the cause before the next send.

If problems persist after running this checklist, the cause is usually specific to your setup. That is when a focused audit, with real placement tests, earns its keep.

Warm-up is not optional for new domains

A brand-new domain has no sending history, so providers treat its first campaigns with suspicion. Sending a large campaign on day one is one of the fastest ways to damage a domain before it has even started.

Warm-up means ramping volume gradually over several weeks: small, engaged batches first, then larger ones as the domain earns trust. It is slow and unglamorous, and it is the difference between a domain that lasts and one that burns out in its first month.

Content triggers beyond the obvious

Beyond heavy images and spammy phrases, several quieter content habits cause filtering: too many links, link shorteners that hide the destination, and mismatched sender names that do not match the sending domain. Each one on its own is small; together they look like a pattern.

The safest content rule is simple: write like a real person writing to one real person. One clear link, honest sender details, and an unsubscribe option that actually works. Filters reward mail that behaves like wanted mail.

Track the right numbers after you send

After a campaign, watch bounces and spam complaints before anything else. Opens are unreliable — privacy features now inflate them — but a rising bounce rate or a complaint spike is a real warning that your list or setup needs attention.

If bounces climb, pause before the next send. Clean the list, check authentication again, and fix the cause. Sending another campaign over a damaged reputation only makes the next recovery longer.

Check the sending setup, not just the message

Before a campaign, confirm which servers are actually authorised to send for your domain, and that every tool you use — your CRM, your outreach platform, your newsletter service — is covered by your authentication records. A common failure is adding a new tool and forgetting to authorise it, so its mail fails checks that everything else passes.

Also check that your sending domain matches the domain in your visible From address. When the two differ, providers notice the mismatch and trust the message less. Alignment between what recipients see and what the records prove is a small detail with an outsized effect on placement.

A pre-send test takes five minutes and saves a campaign

Send the campaign to a handful of test addresses across Gmail, Outlook, and Yahoo before the real send, and check where each copy lands. If a test lands in spam, you have a cheap, private warning — and a chance to fix the cause before thousands of recipients see the same result.

Free spam-score tools add a second layer: they flag content triggers, missing records, and broken links in a single report. Run one on every new template, not just on the first campaign. Templates drift over time as links and images change, and drift is exactly what pre-send tests are for.

Make the checklist a team habit, not a one-time event

A checklist used once is a document; a checklist used before every campaign is a system. The difference shows up in the second month, when a new team member, a new tool, or a new list would otherwise reintroduce the exact problems the first run fixed. Print the checklist, assign an owner for each section, and require a sign-off before any large send.

Review the checklist itself every quarter. Providers change their policies — authentication requirements tighten, bulk-sender rules evolve, and engagement signals shift. A checklist frozen in time slowly becomes a record of what used to work, and the gap between it and current reality is where new deliverability problems are born.

Finally, keep the results. Record placement, bounce, and complaint rates for every campaign alongside the checklist run that preceded it. Over time that record shows which checks actually move your numbers and which ones are ritual — and it gives any future audit a running start instead of a blank page.

One last check: the human test

Before you approve any campaign, read the first lines as the recipient would. Does the sender name look like a real person or business you would recognise? Does the subject promise something the email actually delivers? Would you open it, or would you report it? That thirty-second read catches problems no automated check can see.

If the answer to any of those questions is uncomfortable, fix the message before worrying about the infrastructure. The best authentication in the world cannot save an email that reads like spam to the human it lands in front of.