What warmup's receiving states mean
Warmup runs in two directions, and almost every confusing thing on the warmup page comes from mixing them up. Your mailbox sends warmup to other real inboxes, and other real inboxes send warmup to you. Every percentage on that page — including the one labelled Success Rate — measures the sending direction. The notes described on this page measure the receiving direction. That is why a mailbox can honestly show a high Success Rate and a "Not receiving warmup" note at the same time: both are correct, and they are answering opposite questions.
WarmySender runs your outreach on autopilot with AI agents, across Cold Email, Email Warmup, LinkedIn, Instagram and Multichannel sequences — plus real-time email verification. This guide covers the Email Warmup channel.
"Not receiving warmup" — what triggers it, and what clears it
What triggers it: that mailbox has gone three days without a single warmup email confirmed arriving in its inbox. That is the whole test. It is not a judgement about your domain, your reputation or your setup — it is a count of days since the last confirmed arrival.
What clears it: one warmup email confirmed arriving in that inbox. That is the only thing that clears it. The note disappears the moment one lands.
Two things follow from that, and they are the parts people are usually surprised by:
- No timer runs it out. There is no expiry date and no quiet period after which it lapses. If nothing arrives, the note stays — for a week, a month, indefinitely. Waiting is only a strategy if something is going to arrive.
- It is worked out fresh every time you load the page, from the date of the last confirmed arrival. So it is always current, and it can clear the instant mail starts flowing again without anyone touching anything.
It applies to one mailbox at a time, not to a whole domain. If several of your addresses show it together, that is a coincidence of cause — most often one setting they all depend on — rather than one flag being applied across the domain.
The note tells you that nothing is arriving. It cannot tell you why, and the why is what decides whether waiting helps. Warmup shows active but no emails are arriving has the two-minute test email that separates a passing delivery hiccup (which clears as warmup keeps retrying) from a cause on your own side (which never clears by itself).
One caveat worth knowing so you are not misled by its absence: the note is only shown for mailboxes that warmup expects to be receiving. If warmup is paused on a mailbox, or the mailbox has never sent anything yet, you will not see this note even though nothing is arriving. A brand-new mailbox is quiet because it is new, not because it is stalled.
"Incoming warmup paused" — the one that covers a whole domain
This is a different note with a different meaning, and the difference matters because it changes who can fix it.
"Incoming warmup paused" means we deliberately stopped other inboxes sending warmup to that address, because mail sent there was not getting through. It is a decision we made, not an observation about a count of days. Crucially, it applies to every mailbox on that domain at once — so if you see it appear across several addresses simultaneously, that is expected behaviour rather than a coincidence.
It comes in two kinds: one that carries a restart date and lifts on that day by itself, and one with no restart date that waits for someone on our team to review the address. If yours shows no restart date, message us with the address — it will not lift on its own. The full guide is Why is incoming warmup paused on my inbox?
| Note | Scope | What it means | What clears it |
|---|---|---|---|
| Not receiving warmup | One mailbox | Three days with nothing confirmed arriving | One warmup email arriving. No timer. |
| Incoming warmup paused | Every mailbox on the domain | We stopped sending there, because mail was not getting through | A restart date, or a review by our team |
| Cooling down | One mailbox | Sending volume reduced while placement recovers | About a week of clean placement |
| We can't sign in to check this inbox | One mailbox | Mail is arriving, but we have no permission to look at it | An administrator switching reading on |
"We can't sign in to check this inbox" — the one that is not about delivery at all
The three notes above are all about mail that is not reaching the inbox. This fourth one is the opposite, and it is worth understanding separately because the fix belongs to somebody else: the mail is arriving perfectly well, and we have not been given permission to read it. So there is nothing to count, and the mailbox reports nothing arriving even though nothing is wrong with it.
It only appears on mailboxes managed by an organisation — Microsoft 365 or Google Workspace — because on those, sending and reading are two separate permissions and an administrator grants each one independently. Allowing sending while leaving reading switched off is a very easy thing to do by accident: they are two tick-boxes side by side, and only the sending one usually gets mentioned.
Your sending is completely unaffected while this note is showing. Warmup mail and campaign mail go out exactly as normal, on the schedule you set. The only thing missing is our view of what came back, which is why the arrivals figure sits at a flat zero while everything else looks healthy.
The fix is a single tick-box in your administrator's console and takes about a minute. The exact click-path for both providers, how to do several mailboxes at once, and what to expect afterwards are in Why can't WarmySender read my inbox? — written to be forwarded straight to whoever administers your email.
"Cooling down" — it does not stop you receiving
This is the question we are asked most often about this badge, so here is the direct answer: a "Cooling down" mailbox carries on receiving warmup exactly as normal. Cooling down is a decision about how much that mailbox sends, not about what it is allowed to receive.
It appears when enough of a mailbox's recent warmup landed in spam rather than the inbox. We dial its daily sending volume right down so it stops pushing mail into a place that is not working, and we leave the receiving side completely alone — deliberately, because incoming warmup is part of what rebuilds the reputation that got it here. Cutting off the receiving side would slow the recovery down.
It climbs back on its own once roughly a week goes by with almost nothing landing in spam. Until then it stays low on purpose, and that is the badge doing its job rather than a fault.
Why your Success Rate does not fall when nothing arrives
Success Rate is a sending score. It measures the warmup emails this mailbox sent out and how many of them landed in the main inbox at the other end, rather than in spam. It is calculated entirely from what happened to your mail in other people's inboxes.
So it is structurally incapable of falling because nothing is arriving at your address. There is no path from "no warmup arrived here" to a lower Success Rate, because arrivals are not part of the sum. A mailbox showing 100% Success Rate and "Not receiving warmup" at the same time is not a contradiction and not a glitch — it is two accurate answers to two different questions.
One naming point, because it has confused people and the fault is ours: "Success Rate" and "Inbox Rate" are the same number. The mailbox table column is headed "Success Rate"; the summary card just above it calls the same measure "Inbox Rate". Both mean: of the warmup this mailbox sent and we could confirm, the share that reached the main inbox. If you have been comparing them expecting a difference, there isn't one.
To answer "is this mailbox receiving?", ignore the percentages entirely and read the mailbox row: it shows how much warmup has arrived over the last seven days as a plain count, and carries one of the notes above if there is something to say. There is a worked example in My inbox rate looks great but I'm not receiving warmup emails, and the arithmetic behind the percentage is in Understanding your warmup Inbox Rate.
If two addresses read the same inbox
One setup causes a "Not receiving warmup" note that has nothing to do with your domain or your provider: two or more connected addresses that both read the same inbox. It usually happens by accident, when the incoming username is left as a personal address while the outgoing address is changed.
Warmup confirms an email arrived by finding it in the inbox belonging to the address it was sent to. When several addresses share one inbox they end up competing over the same messages, and the ones that lose the race look as though they received nothing — so they collect the note even though mail is arriving perfectly well.
It is not forbidden, and some people do it deliberately. But results are measurably better when every address reads its own inbox, so if it was not intentional it is worth correcting. To check: open each mailbox's settings and compare the incoming username and server. If two mailboxes show the same pair, they are reading the same inbox. When you connect a mailbox whose incoming details match one you have already added, we now say so at the time.
Frequently asked questions
What exactly triggers the "Not receiving warmup" note?
Three days passing without a single warmup email confirmed arriving in that mailbox's inbox. That is the entire test — it is a count of days since the last confirmed arrival, not a judgement about your domain, your reputation or your settings. It is worked out fresh each time you load the page, so it is always current.
What makes the note go away?
One warmup email confirmed arriving in that inbox, and nothing else. There is no timer, no expiry and no quiet period after which it lapses on its own — if nothing arrives, the note stays indefinitely. That is the important half: waiting only helps if something is going to arrive, which is why it is worth spending two minutes finding out whether anything can.
Does it apply to one mailbox or to my whole domain?
One mailbox. Each mailbox is assessed on its own last confirmed arrival. If several of your addresses show the note at the same time, they are sharing a cause — often a single setting they all depend on — rather than sharing a flag. The note that genuinely covers a whole domain at once is a different one, "Incoming warmup paused".
Does a "Cooling down" mailbox stop receiving warmup by design?
No. Cooling down reduces how much that mailbox sends while its placement recovers, and leaves the receiving side completely alone — on purpose, because incoming warmup is part of what rebuilds the reputation. It appears when enough recent warmup landed in spam, and it lifts by itself after roughly a week of clean placement.
Does the "Not receiving warmup" flag drag my Success Rate down?
No, and it cannot. Success Rate is a sending score: it measures the warmup this mailbox sent and how much of it reached the main inbox at the other end. Arrivals at your address are not part of that sum, so there is no path from "nothing arrived" to a lower score. A mailbox can honestly show 100% and "Not receiving warmup" at once — two accurate answers to two different questions.
Is "Success Rate" different from "Inbox Rate"?
No — they are the same number under two labels, and that is our inconsistency rather than yours. The mailbox table column is headed "Success Rate" and the summary card above it says "Inbox Rate", but both mean: of the warmup this mailbox sent and we could confirm, the share that landed in the main inbox rather than spam.
Nothing is arriving, but I don't see any note — why?
The note is only shown for mailboxes warmup expects to be receiving. If warmup is paused on that mailbox, or it has not sent anything yet, no note appears even though nothing is arriving. A brand-new mailbox is usually quiet simply because it is new. If it has been connected and active for several days and still shows nothing arriving, run the two-minute test email.
What does "We can't sign in to check this inbox" mean, and is my sending affected?
It means mail is arriving at that address perfectly well, but we have not been given permission to read it, so none of it can be counted — which is why the arrivals figure sits at a flat zero while everything else looks healthy. Your sending is not affected at all: warmup mail and campaign mail go out exactly as normal on the schedule you set. It only appears on mailboxes managed by an organisation on Microsoft 365 or Google Workspace, where sending and reading are two separate permissions an administrator grants independently, and it is fixed by a single tick-box in their console rather than by anything you can change. The exact steps for both providers are in "Why can't WarmySender read my inbox?".
Two of my addresses read the same inbox — could that cause this?
Yes, and it is easy to miss. Warmup confirms delivery by finding an email in the inbox belonging to the address it was sent to, so addresses sharing one inbox compete over the same messages and the losers look as though nothing arrived. Compare the incoming username and server across your mailboxes: if two match, they are reading one inbox. Results are measurably better when each address reads its own.
Related reading
- Warmup shows active but no emails are arriving — the two-minute check that tells a passing hiccup apart from a cause on your side.
- Why warmup emails aren't arriving in my inbox — the persistent causes and how to fix each one.
- Why can't WarmySender read my inbox? — when the mail arrives fine but an administrator has not allowed us to read it, and the exact steps to switch reading on.
- Why is incoming warmup paused on my inbox? — the domain-wide pause explained.
- My inbox rate looks great but I'm not receiving warmup emails — a worked example of both being true.
- Understanding your warmup Inbox Rate — how the percentage is calculated.
- How to control your warmup sending volume — where the volume controls live.
- Your warmup dashboard · All documentation