Domain Reputation: How Gmail Scores You, and How to Climb Back

The most frustrating deliverability scenario: authentication is perfect, no blacklist listings, content is clean — and Gmail open rate is still 8%. The missing variable is almost always domain reputation: the score Gmail keeps on your sending domain, invisible — and since August 2026 there's nowhere left to look. This guide is what I know about how it's earned, how it's lost, and how to climb back — level by level.

What the score actually is

Gmail assigns your sending domain one of four grades — Bad, Low, Medium, High — based roughly on the last 30 days of your sending behavior as observed by its users. The dominant input is spam complaints: what fraction of your mail do recipients mark as spam. Engagement (opens, replies, rescues from spam) and volume patterns shape it further. Google doesn't publish the formula, and anyone who claims to know it exactly is bluffing — but after hundreds of domains, the practical rules are consistent:

Complaints are king. A sustained spam rate above ~0.1% drags you down; above 0.3% you're in freefall. (Your ESP's complaint metric counts too — same signal, different window.)
It's a trailing indicator. Today's grade scores what you did one to three weeks ago. Every strategy implication flows from this.
Volume discontinuity hurts. Doubling overnight reads as suspicious even if every recipient loves you.
History compounds. A domain with years of clean behavior survives mistakes that would sink a new or damaged domain.

Check yours now (10 minutes)

Go to postmaster.google.com and add your sending domain.
Verify ownership with the DNS TXT record they give you.
Wait for data — Postmaster populates once you send meaningful volume to Gmail users (roughly a few hundred messages a day; small senders may see sparse data).

Since August 2026 the one behavioral dashboard left is Spam rate — Google removed the Domain and IP reputation displays, so the grade itself is no longer visible; you manage the inputs and read the proxies. Check spam rate weekly, and mind the trap that makes dying domains look calm: it's measured against inboxed mail only, so a collapsing spam rate can mean you're barely inboxing at all. Your own Gmail open-rate trend is the stand-in reputation curve now. The full post-shutdown walkthrough is in the Google Postmaster Tools v2 guide. If you're on a shared ESP sending domain rather than your own, that's a separate problem — your reputation is partially out of your hands, and fixing that starts with a branded sending domain (setup guide).

What each level means for your open rate

These bands are what I've observed across client domains — not official Google numbers, and your mileage varies by industry and audience. But the ordering is reliable. For a broader sample than my client list, the wider industry patterns are in the email authentication data study — 34 top-traffic brands' real mail, analyzed header by header.

Bad: open rate under ~10%. Most campaigns land in spam. Email as a channel is effectively offline.
Low: roughly 10–20%. Significant spam foldering; engaged subscribers still see you.
Medium: roughly 20–35%. Mostly reaching the inbox with intermittent spam placement. This is where "our open rate is fine-ish" hides a slow leak.
High: roughly 35–55%, depending on audience quality. The channel works the way the dashboards promised.

Recovery, level by level

Bad → Low: the hardest gap

This is where recoveries go to die — not because the tactics are different, but because it's the longest stretch with zero visible progress. The protocol:

Cut to your most engaged segment only — people who opened or clicked in the last 30 days. Yes, volume drops 70–90%. That's the point: every send must now generate positive signals.
Fix authentication alignment first if you haven't — you can't out-engage a broken foundation. Your DMARC reports show exactly which senders are failing alignment.
Freeze all promotional blasts. The only mail going out is content your engaged core demonstrably wants.
Wait. Expect two to four weeks where the curve does not move. This is the plateau, and it is normal — Gmail is still scoring your recent past. The senders who fail here are the ones who panic at week three and blast the full list "to test."

Low → Medium: controlled expansion

Once the grade moves, momentum builds — but carefully. Widen the engagement window gradually (30-day → 60-day → 90-day), watching spam rate after each expansion. If spam rate ticks up, pull back a step for another week. This phase typically moves faster than Bad → Low.

Medium → High: prove stability

Gmail is deciding whether your good behavior is a phase or a personality. Consistent volume, engaged-first sending, and zero complaint spikes for a few weeks usually closes the gap. Resume normal campaigns by layering them onto the engaged base, not replacing it.

High: maintenance, not victory

High is an operating state, not a finish line — the routine that keeps it is in this case note. And know that it can still be lost to a single reckless send: one campaign cost this domain six weeks.

What a full climb looks like

Bad to High typically takes six to ten weeks of disciplined sending — not because the steps are many, but because each grade is earned on trailing data. This case note walks a real eight-week recovery, including the three-week plateau where nothing moved and the client (reasonably) wondered if any of it was working. It was. It usually is, if you let the trailing indicator catch up.

One honest caveat: no one can promise you a specific grade or open rate on a specific date — Gmail's filter changes under you, and your history is yours. What's controllable is the behavior the grade measures. Control that, and the grade follows.