SPAM CHECKER // FULL DIAGNOSIS
Spam Checker: Find Out Why Email Goes to Spam, Not Just a Score
A spam score out of 10 tells you almost nothing about a Gmail filter decision. The Inboxes spam checker reports where your real email actually landed at 27+ seed mailboxes, then shows the specific content, structure, and authentication flags that pushed it there.
Inbox placement
67%
··%
· ·
Authentication
checking 130+ blacklists
Sample data. Seed results are estimates, not guarantees.
What is a spam checker?
A spam checker tells you whether an email will trigger spam filters and why. Most only return a score, which hides the outcome that matters. Inboxes checks spam the way mailbox providers decide it: you send your real email from your own ESP to 27+ live seed mailboxes, and the report shows where it landed at Gmail, Outlook, Yahoo, iCloud, GMX, and Zoho, alongside the content and structure flags working against you: link-to-text ratio, image-heavy layouts, misleading subject patterns, a missing List-Unsubscribe header. SPF, DKIM, and DMARC results ride along in the same pass, and fixes come ranked by impact. Seed placement is a directional estimate of a real audience, not a promise, and this is a tool for legitimate senders, not for sneaking spam past filters.
What you get
Spam checker, done properly
Outcome first, score second
Filters do not publish their rules, so a synthetic score is a guess. The board shows the real folder at every seed mailbox, then explains the likely reasons underneath.
Content flags that are specific
Not "avoid spammy words" but the concrete issues in your message: broken List-Unsubscribe, a 620 KB image payload, a tracking domain that does not match your From domain.
Auth checked in the same pass
Half of "spam problems" are SPF, DKIM, or DMARC failures. Every check parses your live headers, so an alignment failure never hides behind a content theory.
Provider-by-provider nuance
Gmail may tab you into Promotions while Outlook inboxes you and Yahoo filters you. One aggregate number would average that into noise; the grid keeps it visible.
How it works
From send to fix list in four steps
Send your real email
Create a check in Inboxes, grab the seed list, and send the actual campaign from your own ESP, exact template, exact sending domain.
Watch the board fill
Within minutes each seed mailbox reports its folder: inbox, Promotions, or spam, grouped by provider.
Read the flag list
Content and structure flags, auth results from your live headers, and any hits across 130+ blacklists, each tied to the placement it likely caused.
Fix, then re-check
Work the ranked list in your ESP and DNS, re-run the check, and confirm the folder actually changed before the real send.
The honest boundary: seed results are directional estimates and nobody can guarantee inbox placement. Inboxes finds the fixable causes, tells you exactly what to change, and monitors the result. No warmup networks, no bot opens, ever. Full detail on the methodology page.