Email integrity, as a service

Catch fake & duplicate signups before they cost you.

SieveGuard detects bot-enumerated and multi-accounting registrations by clustering near-duplicate email addresses, scoring risk, and verifying deliverability — in real time, over a simple API.

Core products

One call catches the bot waves and confirms the mailbox

Bot Anomaly Detection and Email Verification run together as a single action — near-duplicate clustering, structural risk scoring, and mailbox-level deliverability, all in one /v1/emails response. No per-request toggles: one credit weight per screening covers everything.

Bot Anomaly Detection & Email Verification

One call per signup — cluster + risk score + mailbox check, always together

Every /v1/emails call runs the full stack: near-duplicate clustering + a dozen structural heuristics for anomaly detection, then an authoritative mailbox-level check (deliverable / invalid / disposable / spamtrap). One response carries the risk score, cluster id, action band, reasons, and verification status. Bot waves surface as clusters minutes after they start; dead mailboxes get caught before they bounce; spamtraps get force-declined so they can't tank your sender reputation. No per-request toggles — one action, one credit weight.

Near-duplicate clustering

Bot-enumerated and multi-accounting signups get grouped by fuzzy-matching handles as they arrive — the bigger the cluster, the higher the risk.

Risk scoring → action

Every address is scored on structure + cluster size and resolved to allow, verify, or review. Tune the thresholds per list.

Lists & filters

Scope detection to a specific list so duplicates are only evaluated against the right cohort. Per-list tuning knobs.

API-first, multi-tenant

Integrate in minutes with a scoped API key. Strict per-tenant isolation on every layer — your data never mixes.

Built to scale

Bucketed, windowed matching keeps detection fast even with millions of addresses per tenant.

Add-ons

Layer on deliverability + signal verification

Four optional workspace features that plug directly into your detection flow. Pro plans bundle some free; everything stacks on a Stripe-billed slider with pro-rated upgrades and downgrades.

Domain Health

SPF · DKIM · DMARC · MX in one place

In-house DNS checker scores every sender and recipient domain you ingest. Surfaces as a per-record badge so you can flag mismatched / unprotected senders before they cause deliverability damage. Bundled free with Pro plans.

Inbox Placement

See exactly where your mail lands

Send a test from your production sender to a seed list — we report inbox vs spam vs missing per ESP (Gmail / Yahoo / Outlook). 30/60/90-day reputation trend shows whether your deliverability is improving or regressing. Pairs naturally with Warmup — diagnose with Inbox Placement, fix with Warmup.

Warmup

Build sender reputation across every mailbox you sell from

Connect 1, 10 or 50+ sending mailboxes (Gmail / Microsoft / SMTP) and we auto-warm them via partner send/reply loops. Reputation 0-100 per ESP (Google / Microsoft / Other), per-mailbox health-check, optional Pro / Max content tuning. The stepping stone to good Inbox Placement scores — most "we land in spam" problems are mailbox-reputation problems before they're domain problems. IP-level warmup is on our near-term roadmap.

Phone Validation

Catch VoIP & toll-free numbers before SMS

Look up any number's country, carrier, and line type (mobile / VoIP / toll-free / fixed). Cache-first — repeat lookups of the same number are free. Single + bulk modes.

Blacklist Checks

Blacklist coverage on every domain

50+ industry blacklists checked on every domain you ingest. Hit count + listing names land on the matching Domain Health snapshot so deliverability problems surface before they land in production traffic.

Browse all features →See add-on tiers + which Pro plan bundles each →

Free tools · No signup

Try the engines we use, free.

SPF / DKIM / DMARC checkers and a content spam-scorer. Same engines that power the in-app Domain Health and Inbox Placement add-ons — exposed without an account so you can sanity-check a domain in seconds.

SPF checker →DKIM checker →DMARC checker →Email spam checker →

How it works

Send addresses

POST emails to the API — one at a time or in bulk, optionally scoped to a list.

We screen them

Canonicalize, cluster near-duplicates, score, and verify deliverability.

You decide

Get back allow / verify / review per address, plus the cluster and verification advisory.

Built for agencies

Roll up email integrity across every client.

One login, every client workspace. Volume discounts are agreed 1-on-1 — we set a tier ladder for your agency over a short call and demo, then it auto-applies to every client subscription and grows with your roster.

How agency pricing works

1Talk to usA short call and demo to understand your roster and growth plans.
2We agree your ladderA discount ladder set 1-on-1 for your agency — never a published one-size-fits-all.
3Portal unlocksDiscounts auto-apply to every client subscription and grow as you do.

Partner with us

Earn recurring commission on every client you refer.

Join the affiliate program and earn commission on every business you send our way — on both monthly and yearly plans, for a full year. Transparent tracking, no caps on how many clients you bring.

How it works

1ApplyA quick application — we review and approve partner accounts.
2Share your linkRefer businesses with your unique tracking link.
3Get paidEarn recurring commission on every referred subscription for a year.

Screen your first signups in minutes.

Create a workspace, generate an API key, and start sending addresses.