About InboxStack
Built by someone who spent 15 years inside ESPs.
I spent 15 years inside ESP deliverability operations. I watched multi-domain senders struggle with the same problem: they could see that emails weren't landing, but no tool told them why. Every dashboard stopped at "here's your problem." None of them explained the cause.
So I built InboxStack with my co-founder, who came from enterprise deliverability work. We built the diagnosis engine we wished existed when we were on the other side — one that traces the root cause across your ESP, DNS, Postmaster, SNDS, and blocklists, and tells you what to fix first.
No migration. No sales call. Just the answer.
Why we built this
Email teams were drowning in data — starving for answers.
The metrics existed. The signals were there. But nothing connected them, so nobody could turn the raw numbers into a clear picture of which emails were failing and why.
ESP metrics without context
Bounce rates and complaint percentages were reported in isolation, with no way to know what was driving them or which campaigns were responsible.
Provider signals scattered across tools
Gmail Postmaster, Microsoft SNDS, and DNS data lived in separate dashboards — requiring manual cross-referencing to spot patterns.
No correlation between data sources
Even teams with all the right data had no way to connect a DKIM failure on Tuesday to a Gmail domain score drop on Thursday to the spam complaints on Friday. The dots were never joined.
Fixes based on guesswork, not diagnosis
Without knowing why it happened, teams applied generic best-practice changes and hoped something worked, burning time and often making things worse.
Our answer
Three capabilities that replace guesswork.
Each one does exactly one job. Together they tell you where your email is landing, why it changed, and what to fix first.
Alert system
Every signal in one feed.
Brain pulls your ESP campaign data, Gmail Postmaster, Microsoft SNDS and DNS records into one feed. Every data point is timestamped, tied to a sending domain, and checked against everything else, so nothing gets reviewed in isolation.
RCA Inspector
Trace every drop to its cause.
Brain tells you why your inbox rate changed, not just that it did. When signals cluster around an event, the diagnosis engine separates the failure that started it from the symptoms that followed, the way an engineer would after a day of digging.
Resolution Center
A specific fix, not a checklist.
Once Brain knows the cause, it writes a fix sequence for your setup: your ESP, your sending domains, your SPF, DKIM and DMARC records. Every step is ranked by expected impact, so you always know where to start.
Our conviction
Every email team deserves to know exactly what's happening, why, and what to do about it, without needing a specialist on staff.
No black boxes
Every signal, every score, every recommendation is explainable. You always see the reasoning behind what Brain tells you.
No generic advice
Brain's playbooks come from your own data and your own setup, not templated checklists that treat every program the same way.
No guessing
Every fix Brain recommends points to the signals that prove it: the DNS change, the complaint spike, the score drop. Not intuition, not convention, not a best guess.
Who we are
A small team obsessed with email infrastructure.
We're engineers, ESP veterans, and product thinkers who have spent years watching email programs fail for reasons that were entirely preventable. A DKIM key that rotated and never got published. A Gmail domain score that slid for three weeks before anyone looked. The real cause buried under noise that no one had time to untangle. The same avoidable failures, over and over again.
Brain is what we wish had existed when we were on the other side of this problem. We built it because the tools available to email teams were either too shallow to be useful, or too complex to use without a specialist on staff. That gap shouldn't exist. So we closed it.
Talk to us
Questions about how this actually works?
No sales call, no pitch deck. Just the founder, answering what you actually want to know.