What an inbox placement test is, and how to read one

Your sending tool can tell you a message was delivered. It cannot tell you where it was delivered: the inbox, a tab, or the spam folder. An inbox placement test is the closest you can get to looking for yourself.

This guide explains what a placement test measures, how to read the result, and what it cannot tell you.

What an inbox placement test is

A placement test sends messages from your inbox to a seed list: a set of test mailboxes at different mailbox providers, controlled by whoever runs the test. Because the tester can sign in to every seed mailbox, it can see where each message ended up, which no ordinary sending tool can.

The result is a breakdown by provider: for each one, how many seed messages landed in each place, and usually whether each message passed authentication.

Providers: business and personal mailboxes behave differently

A useful seed list covers the providers your recipients actually use, and keeps business and personal accounts apart, because they are filtered differently.

• Business mailboxes, such as Google Workspace and Microsoft 365, are filtered by the provider and also by the recipient organization's own settings: admin policies, allow and block lists, and sometimes a separate security gateway in front of the mailbox.
• Personal mailboxes, such as Gmail and Outlook.com, rely on the provider's consumer filtering. Gmail can also sort personal mail into tabs.

For B2B cold email, most recipients sit on business mailboxes, so business seeds deserve the most weight. Personal seeds still show how your domain reads to consumer filters, and some of your recipients will use personal addresses.

Expect results to differ between providers on the same day. That is normal, not a fault in the test.

The four outcomes

Tests differ in how they count some of these. Outlook's split between Focused and Other is one example: check whether your test counts Other as the inbox, as a tab, or separately, before comparing numbers across tools.

Why authentication results matter

Most placement tests also report whether each message passed SPF, DKIM and DMARC at the receiving end. Read those results first. A failure is the simplest explanation for poor placement, and the easiest to fix. Gmail, Yahoo and Outlook.com all require authentication from bulk senders, and mail that fails can be sent to spam or rejected outright. The records, and how to check them, are in SPF, DKIM and DMARC for cold email.

If authentication passes and placement is still poor, the cause lies elsewhere: the domain's reputation, the content, or the volume.

One test is a snapshot

A single test measures a few messages from one inbox at one moment. Filters adjust constantly, based on what they have recently seen from your domain and from everyone else. A bad result on Tuesday may be gone by Wednesday, and a clean result on one day can hide a slide that started the day before.

A daily series of tests from the same inbox, with the same kind of message, shows what a single test cannot: direction. Is placement stable, improving or slipping? Did the change start when you raised volume, changed the copy, or added a new list?

Small samples move in big steps

Seed lists are small. That is fine, but it changes how you should read percentages.

Here is a worked example. Suppose a test sends to five seed mailboxes at one provider. Each message is then 20% of that provider's result. One message moving from the inbox to spam takes the day from 100% to 80%, which looks alarming and may mean nothing. Two bad days in a row are worth watching. A week drifting downward is a signal.

So:

• Read trends across days, not single days.
• Prefer a rolling figure, such as a 7-day inbox rate, over today's number.
• Compare each provider with its own history, not with the other providers on one day.
• Be wary of precise-looking decimals: 83.3% from six messages is still five out of six.

Reading one result, step by step

Here is a made-up result from a test that sends five messages to each of four providers. The numbers are invented for illustration and do not describe any particular test service.

Read it in this order:

1. Authentication passes everywhere, so the DNS setup is not the problem.
2. Microsoft 365 and Yahoo are clean. Nothing to do.
3. Google Workspace shows one message in spam. That is one message out of five. Compare it with the previous days before reacting.
4. Gmail put three messages in a tab. That is a format question, not a spam problem; the checklist below covers it.

The same table on its own would tell you very little about tomorrow. Next to a week of earlier results, it tells you whether anything has changed.

What a placement test cannot tell you

A placement test measures your setup and your domain's standing against a fixed set of mailboxes. It does not see:

• Your list. Seed addresses always exist. Invalid addresses on your real list cause bounces, and a rising bounce rate damages reputation in a way no seed test will show in advance.
• Your recipients' engagement. Real people reply, ignore, delete, or mark mail as spam. Those reactions, including your spam complaint rate, shape future placement, and seed mailboxes cannot reproduce them.
• Your content, unless you test it. If the test sends its own message, it tells you about the inbox and the domain, not about your copy.
• Specific recipients' filters. One company's security gateway may treat you differently from any seed.
• Scale. A seed test sends a few messages. A campaign sends far more, and volume is a signal in its own right.

A good placement result is a good sign about your setup. It is not a promise about your campaign.

How to act on it

1. Check authentication. If any SPF, DKIM or DMARC result fails, fix DNS first, then retest.
2. Find where it happens. One provider or all of them? Business or personal? A problem at a single provider points to that provider's view of your domain. A drop across the board points to your setup or your sending.
3. Check the trend. One bad day after a good week: keep watching. Several days heading down: act.
4. Look at what changed. Volume increases, new copy, new lists, added links or tracking, and paused warm-up are the usual suspects.
5. Ease off before you push on. Lower volume on the affected inboxes and keep warm-up running while you investigate. How inbox warm-up works covers what steady sending looks like.
6. Treat tabs separately from spam. Tab placement is usually more about format than reputation. Plain, personal-looking messages tend to be sorted differently from newsletter-style HTML.
7. Retest after any change, and judge the change on several days of results, not the first one.

How InboxesNow shows placement before you buy

Every inbox InboxesNow has in stock gets a daily inbox placement test. Each test sends to seed inboxes in the US at Google Workspace (business accounts), Outlook (Microsoft 365, business accounts) and Gmail (personal accounts). For each message it records whether it landed in the inbox, a category tab or spam, and whether SPF, DKIM and DMARC passed.

You see the results on the inbox placement record, per domain and per inbox, before you buy:

• a daily strip for each provider, so you can read the trend rather than one day
• the inbox rate for each provider over the last 7 days
• the SPF, DKIM and DMARC results of the test messages
• all of it next to the domain's warm-up record

The reading rules above still apply: look at the whole strip rather than one day, and weigh any single day lightly. The record is evidence of what the tests found. It is not a guarantee of where your own campaigns will land, which still depends on your list, your copy and your volume.