→ all major services supported (including Gmail, Exchange, iCloud, and Outlook365) → automatic set up for most email services → simple and fast data import from all major email apps (including Microsoft Outlook, Outlook Express, Windows Mail, Thunderbird, Incredimail and more). → touch support for touch-enabled laptops, tablets and hybrid devices → super-fast search that finds any email, contact or attachment in seconds → Online Meetings support (for Zoom, MS Teams, Google Meet) → unique email features, such as Watch for Reply, Snooze Email, or Send Email Later → the interface is customizable in the most comprehensive way on the market (including custom themes and an advanced visual Theme Editor)

InboxStack is an email deliverability intelligence platform built for teams who need to know why their emails aren't reaching the inbox — not just that they aren't. At its core is Brain, a proprietary causal AI engine trained on a 22-year deliverability knowledge base, which correlates signals across your ESP, DNS authentication records (SPF, DKIM, DMARC), Google Postmaster Tools, Microsoft SNDS, and 50+ blocklists to pinpoint root causes instead of surfacing raw metrics.

Most deliverability tools stop at monitoring: they show you a drop in inbox placement or a blocklist hit and leave you to investigate. InboxStack goes further, tracing the actual causal chain — a DKIM misalignment, a reputation dip on a specific sending IP, a content trigger — so you can fix the real problem instead of guessing.

Setup takes minutes with no migration required: forward your email headers for an instant DNS/authentication audit, or connect your existing ESP and Postmaster accounts for ongoing monitoring. Optional seed testing gives you real inbox-vs-spam placement data across major providers.

Built for agencies managing multiple client domains and growing companies who've outgrown basic authentication checkers, InboxStack turns deliverability from a black box into a diagnosable, fixable system.