We help teams send to real, deliverable inboxes — and stop wasting sender reputation on addresses that were never going to convert.
Most email problems aren't marketing problems — they're list problems. Bounces, spam folder placement, and tanking sender scores almost always trace back to bad addresses on the list: typos, abandoned mailboxes, role-based catch-alls, and disposable domains.
The existing tools were either expensive enterprise suites with sales calls attached, or thin wrappers around an SMTP probe that gave up the moment a server throttled them. We wanted something a developer could integrate in an afternoon and a marketer could run a list through without reading a manual.
InboxSure is that. Multi-layer verification — syntax, DNS/MX, SMTP, catch-all, disposable, role-based — exposed via a clean web app, bulk CSV upload, and a straightforward REST API.
TLS in transit, AES-256 at rest. SMTP handshake verification — we never send mail during checks.
Lists that take competitors hours run in minutes. Real-time API responses sub-second on the happy path.
Data minimization. We process what we need to verify, and nothing more. DPAs available for paid plans.
Transparent pricing, no hidden caps. The free plan is genuinely free — no credit card to start.
We're investing in deeper integrations with the tools teams already use — Mailchimp, HubSpot, Klaviyo, SendGrid, ActiveCampaign, Brevo — and writing guides on the topics that drive deliverability: bounce rates, sender reputation, authentication, list hygiene.
Have a tool you want supported, or a deliverability question we haven't covered? Email ask@inboxsure.io — we read every message.
Join thousands of teams using InboxSure to improve deliverability