Warming up
A 99% delivery rate tells you the receiving server accepted the message. It does not tell you which folder it went into. Warmerly sends from your own mailbox to real seed accounts and looks.
A placement test is only meaningful if it travels the route your campaigns travel. Warmerly sends the seeded message over your mailbox's own SMTP connection, with your authentication, from your domain — not from a shared testing relay whose reputation has nothing to do with yours.
The runner connects to each seed mailbox over IMAP and searches Inbox, Promotions, Spam and Junk for the message token, then scores what it finds — inbox scores highest, Promotions well below it, Spam close to zero, missing at zero. Landing in the Gmail Promotions tab is a real outcome with real consequences for reply rate, and a delivery report will never show it to you.
When no seed mailboxes are available, a placement run falls back to Warmerly-controlled mailboxes — which accept nearly everything and would report a flattering score for a sender in genuine trouble. Rather than quietly publish that number, Warmerly marks the run as degraded, labels it in the UI, and refuses to let it feed your health score or raise your sending quota.
Every sending tool reports a delivery rate, and almost every one of them is quoting the same thing: the receiving server returned a 250 and accepted the message. That number is routinely 98% or higher for senders whose mail is going straight into the junk folder. Inbox placement testing answers the question the delivery rate cannot — which folder did it land in, at which provider.
SMTP acceptance and inbox placement are decided at different moments by different systems. The receiving MTA accepts the message during the SMTP conversation, mostly on the basis of whether the address exists and the connection behaved. Filtering happens afterwards, inside the mailbox, where reputation, content and engagement history decide the folder. A message can be accepted with a clean 250 and be sitting in Junk two seconds later.
This is why senders describe the same experience over and over: the dashboard says 99% delivered, the reply rate is 0.2%, and nobody can explain the gap. There is no gap. The mail was delivered — to the spam folder.
A sweep runs automatically each day across accounts that have not been tested in the last twenty-four hours, and you can trigger a test on demand from any mailbox page. Runs that hang are marked failed rather than left pending forever, so a stuck worker never masquerades as a result.
Providers do not agree with each other. It is entirely normal for a domain to place at 96% into Gmail and 88% into Outlook, and the reasons differ: Microsoft weights IP reputation and its own SmartScreen history heavily, Gmail leans harder on domain reputation and engagement. A single blended placement number averages those two into a figure that describes neither.
Because Warmerly seeds across provider families, an Outlook-specific problem shows up as an Outlook-specific problem. That matters operationally: if 70% of your target list is on Microsoft 365 and your Outlook placement is the weak one, that is the number your pipeline actually depends on.
Gmail's Promotions tab is technically delivered and technically not spam. It is also read far less often, and B2B cold mail routed there rarely gets answered. Warmerly scores it well below the inbox rather than counting it as a win, because pretending otherwise makes your dashboard prettier and your pipeline worse.
Real placement measurement needs real seed mailboxes at the major providers. When none are available, the only remaining targets are Warmerly's own warmup pool mailboxes — and those accept essentially everything, so the resulting score is close to 100 no matter how badly the sender is actually performing.
There is a strong commercial temptation to publish that number anyway. Warmerly does the opposite, in three enforced ways. A degraded run never writes to your health score. It is labelled in the interface as limited accuracy. And it is excluded from every downstream calculation that feeds a number — spam scoring, sending capacity, and the public placement counter alike. A trend comparison is only drawn between two runs of the same kind, because comparing a degraded run to a real one measures which targets were available, not a change in your placement.
A single placement percentage hides the shape of the problem. The weekday heatmap on the overview plots placement per day, and the patterns it exposes are diagnostic. A uniform block that suddenly dims on one day usually means a volume spike or a content change on that day. A gradual fade across a fortnight is reputation drift. A single pale column against an otherwise solid grid is very often the day someone imported an unverified list.
The number tells you that something is wrong. The shape tells you when it started, which is most of the way to knowing what caused it.
Above 90% into the inbox proper is healthy for cold sending; above 95% is strong. Below 80% you have a problem worth stopping for. Judge each provider separately — a blended figure can hide a serious Outlook issue behind good Gmail numbers.
Delivery rate measures SMTP acceptance by the receiving server. Placement measures which folder the message ended up in afterwards. Senders whose mail goes entirely to spam routinely show delivery rates above 98%.
It sends a small number of messages from your mailbox, so yes, in the sense that it is real mail from your account. It is a handful of messages per run, not a volume you will notice against a daily allowance.
The daily automatic sweep is enough for steady-state monitoring. Run an on-demand test after anything that changes your sending posture: a new domain, a DNS change, a big list import, or a rewritten sequence.
It means the run had no real seed mailboxes available and fell back to Warmerly-controlled targets, which accept nearly everything. Treat the number as unmeasured rather than good — and it is excluded from your health score for exactly that reason.
Connect a mailbox and Warmerly runs its first placement test the same day, then keeps testing daily without being asked.