Google Postmaster Tools and Yahoo Sender Hub: setup and reading reports

Your ESP can tell you how many messages went out and how many got opened. It can't tell you whether Gmail put them in the inbox or in spam. Only the mailbox provider knows that, and Gmail and Yahoo each run a portal for senders: Google Postmaster Tools and Yahoo Sender Hub. That's where you see complaint rates, SPF/DKIM/DMARC results, TLS coverage and the reasons mail was refused. One thing has changed recently: Google is retiring the domain and IP reputation charts most of us watched first, so they get their own section below.

What Google Postmaster Tools is

Google Postmaster Tools is a free service at postmaster.google.com. It reports on the mail your domain sends to personal Gmail accounts, meaning addresses ending in @gmail.com or @googlemail.com. Mail to company inboxes hosted on Google Workspace is not part of the data. You can sign in with either a regular Google account or a Workspace account.

Everything is aggregated. You won't find out which recipient clicked “Report spam” (there are no addresses anywhere in the tool), and on low-volume days Google may hold back part of the data to protect user privacy. Google doesn't publish the volume at which the charts fill in.

Why postmaster tools matter for email marketers

Mailchimp, Brevo or SendGrid record one thing at the end of the pipe: the receiving server accepted the message. Whether Gmail then files it under Primary, Promotions or Spam is a decision your ESP never sees.

Say open rate slips and the campaign report doesn't explain why. Complaints might have gone up, one of your sending services might have stopped signing with DKIM, or Gmail might be throttling you. Postmaster Tools puts each of those on its own chart, which is usually enough to tell them apart.

Google Postmaster Tools: how to connect

You need a Google account and access to your domain's DNS. Google's own setup steps boil down to this:

1. Sign in at postmaster.google.com and click “Add new domain” on the Manage Domains page.
2. Enter the domain your mail is authenticated with. That is either the DKIM signing domain (the d= tag) or the SPF domain in the Return-Path. When the two are the same, the dashboards count messages that pass either check.
3. Open the domain's menu and choose “Verify domain”. You get a TXT or CNAME record to add at your DNS host (Cloudflare, Route 53, your registrar). Add it, come back and click “Verify”.
4. Optionally, grant teammates access under “Manage users”. This only works for verified domains, and Postmaster won't email them about it, so tell them yourself.

Verification usually goes through right away; the status column can take up to ten minutes to catch up. If it fails, Google suggests waiting a few minutes, double-checking the string in DNS and trying again with a fresh one.

Subdomains that need their own charts are added the same way as the main domain, and they don't need separate verification once the parent is verified. The data isn't real-time either, typically refreshing within 24 hours and sometimes taking longer. All times are UTC, and you can look back 7, 30, 60, 90 or 120 days.

What Google Postmaster reports show

The current interface, which Google calls v2, has six dashboards.

Compliance status. A pass/fail view of Gmail's sender requirements. For every sender it checks SPF and DKIM, DNS records, message formatting, encryption and the user-reported spam rate.

Three more items apply to bulk senders only (roughly 5,000 or more messages a day to Gmail): DMARC, one-click unsubscribe, and actually honoring unsubscribes. Each item reads Compliant, Needs work or No data found. Fixed something and it still says Needs work? The dashboard uses a rolling average over several days, and Google says to check back after seven. Status is shown for the primary domain only, though subdomain traffic feeds into it. There's also a “Deliverability analysis” tool on this dashboard. It gives a recommendation when you send too little, when messages fail, when complaints pass the threshold, or when recipients ignore your mail.

Spam rate. The share of messages that reached the inbox and were then marked as spam by the recipient. Only DKIM-signed mail is counted. Google asks senders to stay below 0.10% and never reach 0.30%. Watch for the inverse trap, though. If Gmail is already filtering a lot of your mail to spam on its own, recipients have little left to report, and the chart drifts toward zero. Google's help page reads a sudden drop from high to zero exactly that way.

Feedback loop. The same complaint data, split by campaign. It needs a Feedback-ID header carrying your campaign identifiers, with the mail DKIM-signed by a domain you've verified in Postmaster. Use it to find which kind of mailing draws the complaints. Identifiers with too few messages or reports won't show up.

Authentication. SPF, DKIM and DMARC pass rates. Don't expect a flat 100% across the board. Google says correctly configured senders typically see 95% or higher for DKIM and DMARC, while SPF runs lower because forwarding and third-party senders break it more often. A DKIM dip usually means a malformed key record or some service (a CRM, a webinar tool) sending as you without signing. Google recommends a separate DKIM key for each third-party sender.

Encryption. The share of mail that traveled over TLS, inbound and outbound. A reading of zero when you know everything goes out over TLS points, per Google, to an expired or revoked certificate or an outdated TLS version. A figure just under 100% is more often forwarding through a server that doesn't encrypt.

Delivery errors. Rejected and temporarily deferred messages as a share of all SPF- or DKIM-authenticated mail, with the reason attached. Google's list of reasons: rate limit exceeded, suspected spam, spammy content, bad or unsupported attachment. It goes on with DMARC p=reject, low IP or domain reputation, domain or IP on a public blocklist (RBL) and a missing PTR record. For temporary failures the advice is to pause briefly, then resume at a slower rate with exponential backoff.

If you think Gmail is misfiling or rejecting legitimate mail, there's a “Report delivery issue” form at the bottom left of the tool. You have to own the verified domain and meet Gmail's sender guidelines, and the message you report must pass SPF and DKIM with a From domain that matches yours.

What happened to domain and IP reputation

For years the two charts everyone watched were Domain Reputation and IP Reputation, rated High, Medium, Low or Bad. They are not in v2. According to Google, every dashboard from the old interface carries over except those two, which are being retired. The help page gives three reasons: senders found reputation data hard to act on, changes in sending behavior showed up on the chart slowly, and since reputation is only one of many deliverability factors, the chart could mislead. Google says a new dashboard will replace it.

Google has postponed shutting down the legacy interface and hasn't given a date, so you may still find the old charts in v1 for now. The API is a different story. The v2 API has no reputation endpoints and the v1 API is being retired, so any monitoring script built on reputation needs rework. I'd move alerts to Compliance status, Spam rate and Delivery errors now. Low reputation hasn't disappeared as a cause, by the way. It still surfaces in Delivery errors as “Sending domain has a low reputation” or “Sending IP has a low reputation”.

Yahoo Sender Hub: setup and what you get

Yahoo's sender portal is Sender Hub, at senders.yahooinc.com.

1. Create a sender profile.
2. Add your domain under Domains and verify it.
3. Under Manage Services, enroll the domain in the Complaint Feedback Loop. The address that will receive reports is confirmed once with a code.

If you joined the Complaint Feedback Loop (CFL) through Yahoo's old form, you have to redo this in Sender Hub or the reports stop. CFL is domain-based and DKIM-only: it keys off the d= domain in your signature. Each time a Yahoo user hits “Spam”, you get an ARF report and can suppress that person from future sends. Most ESPs enroll their customers' domains and process the reports themselves, but it's worth confirming with yours.

For numbers, Sender Hub now has an Insights view under Dashboard, which Yahoo describes as aggregated delivery statistics for your domain. Folder-level placement (how much landed in the inbox versus spam) comes from separate data feeds, the Placement Feed and the Campaign Performance Feed. Access is by request through mail-questions@yahooinc.com.

Yahoo's rules track Google's closely. Keep the spam complaint rate below 0.3%. Yahoo calculates it against mail delivered to the inbox, so if you divide CFL complaints by everything you sent, your number will come out lower than the one Yahoo enforces on. Yahoo deliberately doesn't say what volume makes you a bulk sender. Unsubscribes must be honored within two days.

Google + Yahoo: reading both reports together

A weekly look at both, compared with the week before, catches most problems. Complaints rising at both providers point to the list itself, your frequency or your content. If they rise at only one, look at how that provider's slice of your list differs: signup age, source, segment.

The 0.3% figure means slightly different things at the two companies. For Gmail it's a line you should never reach, with 0.1% as the working target. For Yahoo it's the stated requirement. Both give you two days to process an unsubscribe. And a single spiky day means little when the data lags anyway, so read the week.

Five signals from Postmaster that require action

1. Gmail spam rate at 0.1% or climbing past it. Pause recently added segments and trace where those addresses came from: a new signup form without confirmation, a bought list, an import from an old CRM. The Feedback loop dashboard shows which type of mailing is drawing the complaints. Google also suggests dropping people who never open, and periodically asking subscribers whether they still want your mail.

2. Needs work in Compliance status. The status column spells out what to fix. Give it up to seven days after the change. One quirk worth knowing: the one-click unsubscribe item can go red even when your promotional mail has the header, if messages without it are the ones collecting spam reports.

3. Authentication drops. List every service that sends as your domain: ESP, CRM, transactional provider, webinar platform, helpdesk. Each one needs its own DKIM signature for your domain, and its servers need to be covered by your SPF record. Our SPF, DKIM and DMARC setup guide walks through it.

4. Delivery errors climbing. Read the reason before touching anything. “Rate limit exceeded” is about pace, so send slower and more evenly. Low reputation or an RBL listing won't be fixed by slowing down; that's about complaints and whatever got you listed. Under RFC 5321, a 4xx reply is a temporary failure and 5xx is permanent. Lots of permanent “user does not exist” replies mean the list hasn't been cleaned in a while.

5. Encryption below 100%. Check the TLS logs and the certificate on whatever server hands off your mail, or ask your ESP. It's normally a configuration fix on the SMTP side.

What Postmaster Tools won't show you

Google only sees personal Gmail inboxes. For Outlook and Hotmail you want Microsoft SNDS; for Mail.ru there's Postmaster Mail.ru. You also won't get complainant addresses, unlike a classic ARF feedback loop such as Yahoo's CFL, which sends a report per complaint. Google tries to strip forwarded mail from the charts, but some can slip in. And a blank day usually just means volume was too low to display.

Postmaster data and list validation: the connection

Some of what Postmaster shows grows straight out of the list. Complaints come from people who don't remember signing up, or never did. Permanent “no such user” rejections come from dead mailboxes. Checking addresses before a send takes care of the second problem. It does nothing for the first, because a real address belonging to someone who never asked for your mail passes verification just fine. A live spam trap usually passes too, since to a validator it looks like a working mailbox; the spam traps article explains why. Confirmed opt-in and pruning inactive subscribers are what keep complaints down.

In practice: Postmaster once a week, and an address check after every import and before mailing an old or cold segment.

Checklist: the minimum setup

• Add every domain you sign mail with to Google Postmaster Tools and verify it through DNS.
• Create a Yahoo Sender Hub profile, verify the domain, enroll in the Complaint Feedback Loop.
• Weekly: Compliance status, Spam rate, Authentication, Delivery errors.
• Keep Gmail spam rate under 0.1%; when it creeps up, find the source of the complaints.
• Process unsubscribes within two days.
• When you switch ESPs or add a sending service, check SPF, DKIM and DMARC right away.
• Verify addresses after imports and before mailing old segments.