How to improve email deliverability (complete checklist)

Last updated May 19, 2026Deliverability

Deliverability is the aggregate of authentication, list quality, content quality, engagement, and reputation. Improving it is mostly about removing the things actively hurting you. Once those are gone, the natural state is inbox placement.

Step 1: fix authentication (do this first)

Publish a valid SPF record. Validate with our free SPF checker.
Set up DKIM signing in every ESP that sends as your domain. Validate with the DKIM checker.
Publish a DMARC record, starting at p=none. Validate with the DMARC checker. Progress to p=quarantine and eventually p=reject. See progressive DMARC setup.

Step 2: verify your active list

If you have not verified in 60+ days, this is the next highest-leverage step. Upload your active list to bulk verification. Remove invalid, disposable, disabled, and spamtrap results. Test small batches of catch_all before a full send.

Wire our single-verification API into your signup form. It blocks bad addresses at entry rather than letting them accumulate on your list.

Step 4: segment by engagement

Move dormant subscribers (no opens or clicks in 90+ days) to a separate segment. Either run a re-engagement campaign or suppress them. Continuing to send to inactive subscribers depresses your overall engagement metrics, which depresses your overall deliverability.

Step 5: use a real From address

Send from a person (firstname@yourcompany.com) or a recognizable group (team@, hello@) rather than noreply@.
Make sure the From domain matches your DKIM signing domain (alignment).
Set Reply-To to a monitored mailbox. Replies are positive engagement signals.

Step 6: watch the metrics

Weekly review of these four numbers:

Bounce rate. Keep under 2%.
Spam complaint rate. Keep under 0.1%.
Open rate. Track relative to your historical baseline. Sudden drops point to a deliverability problem.
Inbox-placement rate (via Mail-Tester, GlockApps, others). Should be above 95% for major providers.

Step 7: warm up new infrastructure

New domains or IPs need a deliberate warm-up. See domain warm-up and IP warm-up.

Step 8: content hygiene

Use plain text and HTML versions (multipart).
Keep text-to-image ratio above 60/40.
Use full URLs, not shorteners. Bit.ly and similar are heavily penalized.
Make sure the unsubscribe link is one-click and respected immediately.
Implement List-Unsubscribe headers (Gmail requires this for bulk senders).

Step 9: monitor and iterate

Deliverability is not a one-time fix. Bounce rates creep up. Content drifts toward spam patterns. ISP policies change. Treat it like an ongoing practice: quarterly audits, monthly verifications on active lists, weekly metric reviews.