Inbox placement measures where your accepted emails actually end up: in the inbox, in a tab such as Gmail’s Promotions, or in the spam folder. It answers the question that delivery rate can’t. A campaign with a 99% delivery rate may still have a third of its emails sitting in spam, and nothing in a standard report will tell you directly.
Because mailbox providers don’t report placement to senders, it has to be estimated. Seed tests send a copy of your email to a set of test mailboxes at different providers and check which folder each copy arrived in. Panel data comes from real users who allow a service to see where mail lands. Both are samples rather than a full count, but they reveal patterns, such as Outlook sending you to junk while Gmail does not.
Placement varies by provider, by recipient and over time. Gmail personalises filtering, so two subscribers can see the same email in different places based on their own past behaviour. That’s why a single seed test is a spot check, not a verdict. Tracking placement over several campaigns, alongside engagement trends by provider, gives a more reliable picture.
When placement drops, look first at the usual causes: authentication failures after a DNS change, a jump in complaints, sending to old or unengaged contacts, or a sudden increase in volume. Content matters less than many people think, though broken HTML, link shorteners and misleading subjects can still tip a borderline email into spam.
Before a big Independence Day sale, a Delhi electronics store runs a seed test. Its Gmail seeds land in Promotions, Yahoo in the inbox, but Outlook in junk. It finds that a recently added sending service wasn’t covered by its SPF record, fixes the record, re-tests and sees Outlook move to the inbox.
MailNesto predicts the Gmail tab and folder for each provider in your audience before sending, and can run a real seed test to your own mailboxes to show where a campaign actually lands.