Signup Protection

Block Fake & Disposable Signups

Stop Throwaway Accounts Before They Get In

Fake and disposable email signups slip past most forms. MailRook Email Validation scores the trust of every address in real time — disposable detection, mailbox existence, and domain reputation — so you can accept, challenge, or block at the point of entry.

Disposable & throwaway detection
Real-time API, under 500ms
100 free checks per day

Paste a throwaway address — watch it get flagged.

Checking syntax, MX, SMTP, trust, gateway, and domain profile…

What we check
Mailbox exists and accepts email
Not a disposable address
Not a role or team inbox
Not a catch-all domain
Known mail provider lookup
Enterprise gateway detection
Company and domain profile
API and MCP-ready result
The Problem

Your Signup Form Is Blind to Fake Emails

A throwaway address looks completely normal in the input field. Without a check at the point of entry, fake and disposable signups become bad data, wasted onboarding emails, and fraud you only notice later.

Disposable Addresses

Users sign up with throwaway inboxes to claim trials, abuse promos, or dodge verification — then vanish.

Made-Up Mailboxes

Addresses that pass a regex but point to no real mailbox — your onboarding emails bounce into the void.

Burner Domains

Days-old domains on abused networks and risky TLDs — strong fraud signals a blocklist hasn't caught yet.

Bot Signups

Digit-heavy, random local parts that look automated rather than human — flagged even on a clean domain.

The Signals

What Goes Into the Trust Score

Every check returns a 0–100 domain trust score and an itemised breakdown — so a block is auditable, not a black box.

Disposable Detection

Flags known throwaway providers and new ones hiding on shared disposable infrastructure.

Mailbox Existence

SMTP-level verification confirms the address can actually receive mail — and flags catch-all domains.

Domain Age & Reputation

Days-old domains, abused networks, and near-expiry registrations all lower the trust score.

Risky TLDs & Patterns

Known-abused TLDs and bot-style local parts add a cheap, effective fraud prior to the score.

Real-Business Signals

A live website, e-commerce stack, and public org details confirm a real business stands behind the domain.

One Structured Verdict

Score, disposable flag, mailbox status, and domain profile in one JSON response you can build logic on.

Process

Accept, Challenge, or Block — in the Moment

1

Call the API on submit

When a user registers, send the address to MailRook Email Validation from your backend — a single request, under 500ms.

2

Read the trust score

Get back a 0–100 trust score, disposable flag, mailbox status, and a full domain profile as structured JSON.

3

Act on your thresholds

Let trusted users straight through, challenge the in-between, and block the throwaway — your rules, your thresholds.

{
  "email": "[email protected]",
  "trust_score": 12,
  "isv_nodisposable": false,
  "isv_deliverable": false,
  "result": "undeliverable"
}
Use Cases

Who Uses Signup Protection?

SaaS & Free Trials

Stop trial abuse and fake accounts that inflate metrics and burn onboarding resources.

E-commerce & Promos

Block throwaway addresses created to farm welcome discounts and referral credit.

Marketplaces & Communities

Keep fake and bot accounts out so your platform stays trustworthy for real members.

Fintech & High-Risk

Add an early fraud signal at registration, before KYC and downstream review.

Pricing

Start Free — Scale With Your Signups

100 free checks per day, no credit card required. Upgrade when your volume grows.

Free forever
$0 / month

Perfect for developers and small teams getting started with email validation.

  • 100 free checks per day
  • Single & bulk email validation
  • REST API access
  • Syntax, DNS, MX & mailbox checks
  • No credit card required
Get started free
Pay as you go
One-time purchase
$39

10,000 credits — use at your own pace. No subscription, no expiration.

Choose pack size
  • 10,000 verification credits
  • Credits never expire
  • Everything in the free plan
  • One-time payment — no recurring fees
  • $0.0039 per verification
Buy credits
High volume
Custom

For businesses and teams that need high-volume validation or dedicated infrastructure.

  • Unlimited or high-volume checks
  • Everything in the free plan
  • Priority support
  • SLA & dedicated infrastructure
  • Custom integrations & onboarding
Contact us
Questions?

Signup Protection FAQs

MailRook Email Validation combines several signals into a single domain trust score: whether the address is a disposable/throwaway provider, whether the mailbox actually exists at the SMTP level, the age and reputation of the domain, risky TLDs, and shared disposable infrastructure. You get the score plus an itemised breakdown, so you can accept, challenge, or block in the moment.
Yes. Beyond a static blocklist, MailRook Email Validation detects new throwaway domains by their infrastructure — shared MX hosts, MX/A-record IPs, and nameserver sets used by known disposable providers — plus username heuristics for bot-style local parts. This catches burner domains created hours ago that blocklists have not seen.
No. A single check returns in under 500ms, so you can validate inline as the user submits the form. Real users with normal addresses pass instantly; only low-trust or disposable addresses get challenged or blocked, based on the thresholds you set.
Call the REST API from your backend when a user registers — a single request returns the trust score, disposable flag, mailbox existence, and full domain profile as structured JSON. Use the score to accept, send to email verification, or block. AI agents can call the same checks through our MCP server.
Yes. MailRook Email Validation performs SMTP-level verification to confirm the mailbox accepts mail, and flags catch-all domains where a positive result cannot be trusted. That tells you whether an address was really made up at signup.
Yes. Every account gets 100 free checks per day — no credit card required — so you can wire signup protection into your form and test it end to end before upgrading.

Keep Fake Signups Out Today

Wire signup protection into your form in minutes. 100 free checks per day, no credit card required.