Updated · 9 min read
Google Postmaster Tools: a walkthrough for people who actually send email
Gmail handles roughly 40% of global inbox share. If your domain reputation with Gmail is bad, nothing else you're doing matters — a chunk of your list literally won't see the mail. Postmaster Tools is Gmail's only public window into how it sees your domain. Free. Ten minutes to set up. Ignored by most programs. This is the walkthrough of every tab worth watching and what to do with the data when it finally shows up.
By Justin Williames
Founder, Orbit · 10+ years in lifecycle marketing
Setup in ten minutes
Head to postmaster.google.com and sign in with a Google account tied to your domain. Add the sending domain — marketing.brand.com, say. Gmail asks for a TXT record to verify ownership, same pattern as Search Console. Drop it in DNS and you're done.
Add each subdomain separately. Reputation is scored per subdomain, which means marketing.brand.com and accounts.brand.com need their own Postmaster entries. If you share access with the team, two people is the minimum — the CRM lead and someone on the engineering side who owns DNS. Access runs through Google Workspace accounts, not shared credentials. Document the handoff. A Postmaster lapse (forgotten login, nobody monitoring) is exactly how reputation drifts six weeks without anyone noticing.
Data starts flowing 24 to 48 hours after verification, but the charts need minimum volume — a few hundred Gmail recipients per day — before they populate meaningfully. Below that, everything is blank or sparse. Which is information too: you don't have a Gmail deliverability problem yet because you don't have meaningful Gmail volume yet.
Domain Reputation — the one chart that matters
Domain Reputation rates your domain on a four-tier scale: Bad, Low, Medium, High. This is the chart. Every other tab in Postmaster Tools is secondary to this one.
High means inbox placement on Gmail is effectively solved. Medium means it's fine most of the time. Low or Bad means 40% of your audience has a problem you can't see from the ESP dashboard.
What to act on, in order of severity:
High, holding steady: nothing to do. Keep doing what you're doing.
Medium climbing to High: you're improving. Don't change anything.
High drifting to Medium: investigate the last two weeks. Frequency bump, new segment, a subject line that spiked unsubscribes. Catch it now before it drops further — reputation moves quickly down and slowly up.
Medium drifting to Low: urgent. Cut to users who opened or clicked in the last 30 days. Audit the list for dormants.
Low or Bad: stop broad sending entirely. Engaged-only until it recovers.
Medium by itself isn't bad, by the way. Gmail delivers most of your mail to the inbox on Medium and applies more scrutiny to borderline cases. High is better but not essential. The thing to panic about is direction, not absolute level — a Medium that's held for months without moving is fine; a High that just dropped to Medium last week is the signal. The rating runs on rolling 7-day windows, so a spike in complaints can drop you a full tier inside a week.
IP Reputation — less useful than it looks
Same Bad/Low/Medium/High scale, but for the sending IPs associated with your domain. On a dedicated IP this tracks closely with your domain reputation. On a shared IP — most smaller programs — it reflects the pool, which means your neighbours' behaviour.
In 2026, Gmail weighs domain reputation more heavily than IP reputation. Worth monitoring. Secondary to everything in the previous section.
Spam Rate — your complaint rate on Gmail specifically
Spam Rate is the percentage of Gmail-delivered mail that users mark as spam. Gmail uses this signal more directly than almost anything else to decide your reputation, which means it's the number to watch weekly.
Below 0.1%: healthy. No concern.
0.1–0.3%: warning zone. Gmail is starting to treat you as spam-adjacent. Investigate frequency, unsubscribe flow, dormant audience.
Above 0.3%:emergency. Gmail will put your mail in the spam folder or reject it outright. Cut immediately to the top 20% engaged slice and go find the root cause — new segment, frequency change, a campaign that over-indexed on complaints. Recovery is 6 to 12 weeks once the rate comes back down. That's not a typo.
Gmail, uniquely among major ISPs, doesn't provide a feedback loop for individual complaints. You see the aggregate spam rate and that's it — no list of who complained. Your ESP's FBL covers Yahoo, Microsoft, AOL, Comcast; Gmail is a rate-only signal. Annoying but fixed policy. The spam complaints playbook covers the four levers that actually reduce the rate; Postmaster's Spam Rate is the canonical measurement.
Authentication — the chart that should always be green
The Authentication tab shows SPF, DKIM, and DMARC pass rates for Gmail-delivered mail. All three should sit at or near 100%.
If SPF drops, check that your ESP's sending servers are in your SPF record. If DKIM drops, check DKIM signing is on in the ESP and the selector is published in DNS. If DMARC drops, check your policy and alignment. Rates below 95% mean authenticated mail is failing a check somewhere — almost always a config issue, almost always easy to fix once you see which of the three has slipped. The SPF/DKIM/DMARC explainer covers each protocol.
Delivery Errors — where things are being rejected
Delivery Errors shows the percentage of your mail Gmail refused at the SMTP level, broken down by reason. The big categories: "sender IP reputation", "policy-related", "content-related", "too-many-recipients".
In a healthy program this chart is near-empty. Gmail accepts most mail and filters at the inbox or spam-folder level rather than rejecting at SMTP. A spike in "sender IP reputation" rejections means your IP reputation has dropped below Gmail's acceptance floor. A spike in "policy-related" means your content is hitting specific filter rules — usually an image-to-text ratio problem or a URL shortener Gmail has flagged. Chase the spike to the category, then the category to the campaign.
How often to check
Screenshot the Domain Reputation chart weekly and keep the images in a shared drive. You want the trend, not the current state. A High that just dropped from 60 days of steady High is a very different signal from a High that just climbed from Medium, and the dashboard alone doesn't show you which one you're looking at.
The Deliverability Management skillbuilds the Postmaster check into a weekly cadence automatically. If you're running manually, put it on the calendar. Every Monday. Ten minutes. The one deliverability habit with the highest return on the time spent.
This guide is backed by an Orbit skill
Related guides
Browse allDedicated vs shared IP: the real decision
Every ESP sales conversation pitches the dedicated IP as an upgrade. For most lifecycle programs it isn't — it's a trade, and often a losing one. Here's the volume threshold that actually justifies dedicated, the risks most teams don't anticipate, and when the shared pool is genuinely the better call.
Spam complaints: the playbook for detecting and reducing them
Spam complaints are the hardest-hitting negative reputation signal in email. They compound faster than bounces and recover slower. This is the playbook — what actually triggers them, how to catch them early, and the four levers that reliably bring the rate back down.
The deliverability mental model: one picture for authentication, reputation, content, and monitoring
Every deliverability guide covers one piece — SPF, DKIM, DMARC, BIMI, reputation, warmup. What's missing is the systems-level picture that ties them together. This is the one diagram a senior operator needs: how mailbox providers decide whether your email reaches the inbox, and where each piece of the stack plugs in.
Email deliverability — the practitioner's guide
Deliverability isn't a setting. It's the running total of every send decision you've made since you bought the domain. Four pillars hold it up. Break one and the whole program starts leaking.
IP warm-up in Braze — the playbook that actually holds
A fresh dedicated IP has zero reputation on day one. Most warm-up guides fixate on ramp speed and ignore the harder question — which users get the send each day. Here's the schedule, the Random Bucket Number trick, and the day-10 mistake that ruins most of them.
Apple Mail Privacy Protection, four years in
Apple broke the open rate in 2021. Half the lifecycle industry is still pretending it didn't happen. Four years on, the programs that actually adapted are beating the ones that kept optimising a metric that doesn't exist anymore.
Found this useful? Share it with your team.
Use this in Claude
Run this methodology inside your Claude sessions.
Orbit turns every guide on this site into an executable Claude skill — 54 lifecycle methodologies, 55 MCP tools, native Braze integration. Pay what it's worth.