Inbox Placement
Inbox placement describes where accepted email appears. Delivery logs cannot establish placement, and seed tests represent a sample of mailboxes.
Inbox placement describes where a message appears after a receiving system accepts it. It may reach an inbox category or a spam folder. Server acceptance alone does not identify that destination.
Gmail's Promotions tab is an inbox category, not its spam folder. If a report measures only Primary placement, label it that way instead of counting every other category as spam.
What a placement test can show
A seed test sends to a set of test mailboxes and records where those messages appear. That result describes the tested accounts. Their history and filtering can differ from the real recipients on your list, so the sample does not establish a placement rate for the whole audience.
Provider delivery logs can identify acceptance and failures but generally cannot see the recipient's folder. Opens are also limited evidence because image loading does not necessarily represent a read.
Investigate affected mailboxes
Compare reports from real recipients with the sent message, authentication results, and changes in sending volume or audience source. Check SPF, DKIM, and DMARC where applicable. Passing authentication supports the sending identity. It does not guarantee a particular folder.
Use the spam troubleshooting guide to investigate the message and provider involved.