SieveGuard is an email-integrity API for product, growth, and deliverability teams. It clusters near-duplicate email addresses as they arrive, scores bot and multi-accounting risk, and verifies deliverability — catching fake and duplicate signups before they cost you money, skew your metrics, or drag down your sending reputation.
Signup fraud is quiet. Bot-enumerated and multi-accounting registrations don’t announce themselves — they inflate your user counts, burn free-tier resources and email credits, and quietly poison your lists until deliverability craters. Most teams only notice once the damage is done. SieveGuard was built to catch it at the front door: at the moment of signup, in one call, with a clear verdict you can act on.
Every API call runs the full stack — near-duplicate clustering, structural risk scoring, and authoritative mailbox verification — so you get a decision, not a pile of raw signals to stitch together yourself.
Beyond "is this address real?", SieveGuard scores the domain (SPF / DKIM / DMARC / MX), checks blacklists, tests inbox placement, and warms sending mailboxes — the whole picture of whether your mail lands.
A suite of unauthenticated developer tools — SPF / DKIM / DMARC checkers, a blacklist checker, an SMTP test and more — because the best way to trust an email-integrity API is to use its building blocks first.
SieveGuard is an independent, self-funded business operated from Republic of Malta, with customer data held in AWS Frankfurt (eu-central-1). No investors, no growth-at-all-costs mandate — just a focused product and a direct line to the person building it.