Deliverability monitoring: the dashboard to check every week
Deliverability monitoring means checking spam rate, bounce rate, inbox placement, blocklist status and authentication every week before a domain breaks.
ON THIS PAGE · 8 SECTIONS
- What deliverability monitoring actually checks
- The five numbers to check every week
- Where each number comes from
- What does Google Postmaster Tools actually tell you?
- Running the weekly review
- Build your own dashboard or buy one
- A worked example: a 10-domain dashboard
- Questions about deliverability monitoring
THE SHORT VERSION
- Deliverability monitoring is a weekly check on five numbers: spam complaint rate, bounce rate, inbox placement rate, blocklist status and authentication pass rate.
- Google requires bulk senders to keep spam complaints under 0.3% in Postmaster Tools and recommends staying under 0.1% for a safety margin.
- Postmaster Tools and Microsoft SNDS are free and cover most of it. Seed-list placement testing and a blocklist checker fill the two gaps they leave.
- A spreadsheet pulled by hand works under 10 domains. Past that, the manual pull itself becomes the thing that breaks the routine.
- One bad number does not mean pause everything. It means check which domain, how fast it moved and whether the cause is content, volume or a list problem.
Deliverability monitoring is the weekly habit of checking a small set of sending health numbers, spam complaint rate, bounce rate, inbox placement rate, blocklist status and authentication pass rate, so a problem gets caught on one domain before it spreads to the rest of your sending infrastructure. It is not a one-time setup step. It is a recurring review with a named owner and a threshold for each number.
Most teams set up SPF, DKIM and DMARC once, warm up their domains and never look again until replies stop coming in. By then the damage is a week or two old and the fix takes just as long. The numbers below exist to catch the problem on day two instead of day fourteen.
What deliverability monitoring actually checks
Deliverability has two layers and monitoring only covers the second one. The first layer is delivery: did the mail server accept the message. The second is deliverability: did it land in the inbox, not spam. A send can show zero bounces and still sit in spam for every recipient. Monitoring is the practice of watching the second layer on a schedule, because mailbox providers change their read on a domain's reputation continuously, not just at setup.
The providers that matter are Google, Microsoft and Yahoo, because together they host most B2B inboxes. Each one scores a sending domain and IP on recent behavior: how many people mark mail as spam, how many addresses bounce, whether authentication passes and how a seed account's placement looks. A domain's reputation can move from good to flagged inside a single bad week of sending into a stale list.
The five numbers to check every week
Pull these five every week, per sending domain, not just at the account level. A system of 10 domains with one bad domain still looks fine in an averaged dashboard. It does not look fine domain by domain.
Source: Google, Gmail sender guidelines, 2026
- Spam complaint rate. From Google Postmaster Tools and Microsoft SNDS. This is the single number that gets a domain throttled.
- Bounce rate. From your sending tool's delivery log. A rising bounce rate on an aged list usually means the data decayed, not that deliverability broke.
- Inbox placement rate. From a seed-list placement test, since no mailbox provider reports this directly.
- Blocklist status. From a blocklist checker run against your sending IPs and domains.
- Authentication pass rate. From your DMARC aggregate reports, confirming SPF and DKIM still align after any DNS change.
Where each number comes from
None of these five live in one tool. That is the main reason monitoring breaks down: the data is scattered and nobody owns pulling it together.
| Metric | Where it lives | Cost |
|---|---|---|
| Spam complaint rate | Google Postmaster Tools, Microsoft SNDS | Free |
| Bounce rate | Your sending or outreach tool's delivery log | Included |
| Inbox placement rate | Seed-list testing tool (GlockApps, Mailreach, Warmup Inbox) | $30 to $150 per month |
| Blocklist status | A blocklist checker (MXToolbox or similar) | Free to low cost |
| Authentication pass rate | DMARC aggregate report viewer | Free to low cost |
The five numbers, where to pull each one and what it costs to track.
Google Postmaster Tools and Microsoft SNDS only work on domains that send enough volume for the provider to have a reputation score on file, so a brand new domain shows blank data for its first week or two. That gap is exactly why a seed-list placement test matters during a new domain's warmup window: it is the only signal you get before the providers start reporting.
What does Google Postmaster Tools actually tell you?
Postmaster Tools reports domain reputation as a bucket, not a number: bad, low, medium or high. The spam rate graph lags real time by about a day and it only populates once a domain sends enough volume to Gmail addresses for Google to score it. Four graphs matter most:
- Spam rateOne graph, one threshold. Anything sustained above 0.3% is an active problem, not a blip to watch.
- Domain reputationA drop from high or medium to low or bad is the clearest early warning you get, often a day or two before complaint rate visibly spikes.
- IP reputationOnly relevant if you send from dedicated IPs. Most cold email setups run on shared ESP infrastructure, so this graph stays empty.
- AuthenticationShows the share of mail passing SPF, DKIM and DMARC. A drop here almost always traces back to a DNS record someone changed without checking the chain.
Microsoft's Smart Network Data Services (SNDS) covers the same ground for Outlook and Hotmail addresses, with a complaint rate and a trap-hit count instead of a reputation bucket. Register each sending IP range separately; SNDS does not infer anything you have not registered.
Running the weekly review
The review takes 15 to 20 minutes once the pulls are set up and it should happen on the same day every week so a slow drift gets caught before it becomes a cliff.
- Pull the five numbers per domain. Not an account average. A single bad domain disappears inside a blended number.
- Flag anything that crossed a threshold. Spam complaints above 0.2%, bounce rate above 2%, any new blocklist hit, authentication pass rate under 95%.
- Check what changed on that domain. A new list, a higher daily volume, a new subject line pattern or a DNS record someone touched.
- Decide pause, fix or watch. Pause sending from that domain if the spam rate is climbing fast. Fix the cause if it is clear. Watch one more cycle if the number is borderline and the cause is not.
- Log the decision. A one-line note on what moved and what you did about it saves the next review from re-diagnosing the same domain.
Give this review a named owner. Whoever runs the sending infrastructure day to day is usually the right person, not whoever happens to notice a reply rate drop two weeks later.
A dashboard nobody owns is a report nobody reads.
FROM THE YARD
We have watched a domain's Postmaster Tools reputation drop from medium to bad inside four days after a list got reused without a fresh verification pass. The bounce rate barely moved, maybe half a point. The complaint rate was what gave it away and only because someone was looking at it that week. By the time replies dried up it would have taken three weeks of near-silence on that domain to earn the reputation back. Watching the leading number cost us 15 minutes. Not watching it would have cost a month of sends.
Build your own dashboard or buy one
THE SPREADSHEET WAY
- Works fine under 10 sending domains
- Free beyond the placement-testing tool
- Someone has to remember to pull it every week
- No alert when a number crosses a line between reviews
THE PLATFORM WAY
- Pulls Postmaster Tools, SNDS and placement data automatically
- Alerts the moment a threshold is crossed, not a week later
- Costs $50 to $300 a month depending on domain count
- Worth it once a single missed review has cost real pipeline
Most teams start with the spreadsheet and switch once the domain count or the cost of a missed warning sign makes the manual pull the weak link. There is no fixed domain count where that switch has to happen. It happens the first time a problem sits unnoticed for more than a week because nobody pulled the numbers.
A worked example: a 10-domain dashboard
Here is an example week for a team running 10 sending domains, two inboxes each, roughly 400 contacts per day in total. The numbers are illustrative, not a real client's data.
| Domain | Spam rate | Bounce rate | Placement | Status |
|---|---|---|---|---|
| domain-01 to 07 | 0.02% to 0.08% | 0.6% to 1.4% | 92% to 97% inbox | Healthy, send as planned |
| domain-08 | 0.19% | 1.1% | 85% inbox | Watch, trending up for two weeks |
| domain-09 | 0.34% | 2.3% | 61% inbox | Pause, list reused without re-verification |
| domain-10 | 0.03% | 0.9% | 94% inbox | Healthy, newest domain, still in warmup |
Example dashboard: seven domains healthy, one trending the wrong way, one past the line and paused.
Domain-09 crossed the line Google treats as a hard ceiling, 0.3% spam complaints, alongside a bounce rate and placement rate that both moved the same direction. That pattern, three numbers moving together, points at a list problem rather than a content or volume problem. The fix is a fresh verification pass on that list, a week of reduced volume on that domain only and a placement retest before it goes back to full send.
Questions about deliverability monitoring
How often should I check deliverability metrics?
Weekly, per sending domain. Daily is overkill for a stable system and tends to get skipped after the first few weeks. Monthly is too slow. By the time a monthly check catches a problem, the domain has usually been sending into spam for three or four weeks.
What is a good spam complaint rate for cold email?
Under 0.1% is the safe target. Google's hard ceiling in Postmaster Tools is 0.3% and crossing it triggers throttling that can take a week or more of clean sending to reverse.
Do I need a paid tool to monitor deliverability?
Not at a small scale. Google Postmaster Tools and Microsoft SNDS are free and cover spam rate, reputation and authentication. The only gap they leave is inbox placement, which needs a seed-list testing tool, typically $30 to $150 a month.
What should I do when a domain's spam rate crosses the threshold?
Pause sending from that specific domain, not the whole system. Check what changed first: a reused list, a higher volume or a new DNS record. Fix the cause, hold volume down for a week, then retest placement before returning to full send.
Does bounce rate or spam rate matter more?
Spam rate is the one mailbox providers act on directly, so it moves reputation fastest. Bounce rate matters because it is usually the earliest symptom of the same root cause, a stale or reused list, so a rising bounce rate is worth treating as an early warning for spam rate, not a separate problem.
Monitoring will not fix a list that was never verified or a message that reads like a mass blast. It only tells you where the damage is starting before it spreads to every domain you own. Pair the dashboard with a real fix for whatever it flags and treat a crossed threshold as a reason to check the domain, not a reason to panic about the whole system.
Want your sending infrastructure watched every week instead of after replies stop? See how the system handles it or book a call to talk through your current setup.
Sources: Google, Gmail sender guidelines, 2026, Warmforge, Email Deliverability Statistics, 2026, Amplemarket, 2026 Cold Email Benchmarks.