You ship a campaign. The send report shows 99% delivered. A week later, a customer says they never got it. "Delivered" usually means the recipient's mail server accepted the message at SMTP. It does not mean the message landed in the primary inbox. InboxIssue tests against real corporate mailboxes with the full security stack enabled and tells you where the message actually went.
M365 inbox rate dropped 6% from prior send. Subject line "Final notice" triggered Defender heuristic. Re-test with neutral subject before scaling.
Most inbox-placement tools test consumer email. Gmail and Yahoo seed accounts on basic configurations. That tells you about consumer placement and very little about business placement. Corporate inboxes run threat scanners, link protection, attachment inspection, and spam policies that consumer inboxes do not. A message that hits Gmail's primary inbox can land in a corporate Junk folder for reasons the consumer-side test will never surface.
If your prospects, customers, partners, or transactional recipients are on Microsoft 365 or Google Workspace business plans, you want to know how the message looks to them, not to a stripped-down seed account. That is the gap InboxIssue fills. InboxIssue is part of DuoCircle's broader Deliver group, alongside Outbound SMTP, the Developer Email API, and Cold Email Outreach (NuReply).
Real corporate mailboxes, real placement results, real headers. An API to wire it into CI, deployment pipelines, and monitoring. Built and supported by the same team.
Microsoft 365 and Google Workspace business plans with the full security stack enabled: threat scanners running, link protection rewriting URLs, attachment inspection, and spam policies tuned to enterprise defaults. Not consumer seed accounts. The actual security layers your business recipients use.
You see exactly where the message landed: primary inbox, Junk, quarantine, or rejected outright. You see why. You get the headers back so you can debug instead of guessing. Sender-side dashboards say 99% delivered when 30% landed in Junk. Placement testing gives you the truth.
Send a request to start a test, poll for results, or receive a webhook when the test finishes. Wire it into CI so a placement regression fails the build before customers see broken transactional mail. Hooks into deployment pipelines, sending platforms, and monitoring stacks.
SPF, DKIM, and DMARC are evaluated the way the recipient's mail server actually evaluates them. Misalignment that an authentication validator misses but a real receiver catches shows up here. The test reflects the receiver, not the theory.
Pre-flight a campaign before it sends. Validate a welcome email actually reaches the user's inbox during onboarding. Prove a SPF, DKIM, or DMARC fix actually closed the regression. Compare two sending paths through the same mailbox to see which one places where.
InboxIssue is built and supported by the same team. The developer who shipped the test endpoint answers the support email when something looks off. No SDR layer between you and the people who can actually fix the test result.
You only send to consumer mailboxes (Gmail, Yahoo, iCloud) and do not care about business placement. A consumer-focused testing tool is a simpler, cheaper fit for that profile.
You need long-term reputation monitoring. Rolling spam-trap hits, blocklist trending, and sender-reputation scores over time are a different category. Placement testing is point-in-time validation, not continuous reputation monitoring.
You haven't set up SPF, DKIM, or DMARC yet. Fix that first. Placement testing is most useful when authentication is already correct. We can also help with the foundation work through SPF Management and DMARC Reporting.
When you contact us about inbox placement testing, you talk to an expert who has actually debugged placement regressions across Microsoft 365 and Google Workspace business tenants. We tell you whether you need API integration in CI, ad-hoc pre-flight tests, or a fix one layer up at authentication.
Reference calls with existing InboxIssue customers are available on request. Most enterprise customers prohibit logo use to keep vendors from leveraging their brand. Those same customers will take a phone call from a serious prospect to vouch for what we actually do in production.
Same-day response. Real expert on the call. We tell you whether placement testing fits your sending pattern and how to wire it in.