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Threat Intelligence

Email Domain Reputation Check The sender’s domain, its listings and its mail records.

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Examples
Output

What the check returns

user@example.comFictional example
Domain
example.com
Checks the report names
Domain reputationData breachesMail server securityEmail reputationEmail validationPattern analysis

The MX, SPF and DMARC records behind mail server security are fields of the API response; the report names the check.

Fictional example dated 2026-09-01. Not a current result for this value.

Check a sender before you reply, click or pay: listings for the address and its domain, disposable providers, MX, SPF and DMARC. It does not test whether the mailbox exists. Free, no signup.

Create free accountAPI Documentation

No credit card required · Free API key

curl -d "email=you@example.com" https://ismalicious.com/api/keys/instant

250 free requests/month · instant API key · no signup form

Capabilities

Key features at a glance.

Scam blocklists

Curated scam and fraud blocklists built from abuse reports and threat feeds.

Sender domain

Reputation, age and listing history of the domain behind the address.

Disposable addresses

Known throwaway providers are flagged, the usual cover for fake accounts.

Paste the whole message

Sender, links, phone numbers and wallets are extracted and checked together.

REST API

Screen addresses at signup, in CRM imports or in fraud pipelines.

Evidence, not just a score

Every verdict names its sources, so an analyst can defend the decision.

Applications

Use cases to evaluate first.

  1. Suspicious senders

    Check the sender of an unexpected invoice or job offer.

  2. Signup fraud

    Flag disposable and listed addresses at registration.

  3. BEC and phishing response

    Enrich reported emails with sender reputation and related infrastructure.

  4. Marketplace trust

    Screen counterparty addresses on listings and transactions.

Free account

What a free account adds to your lookups

An API key, monitoring and a report history for the checks you run here.

Create free account

Website lookups: no monthly cap · 250 API requests/month · free API key · no credit card required

  • API key250 requests a month through the REST API, from your dashboard.
  • MonitoringUp to 5 domains or IPs, re-checked every day, with an email when their status changes.
  • Report history10 saved reports over 30 days, to revisit and compare.
  • Bulk checksUp to 10 indicators in one request.
FAQ

Frequently asked questions.

How do I check if an email address is a scam?

Paste the address. isMalicious matches it against scam and fraud blocklists, inspects the sending domain and returns a verdict with its evidence.

Does this reveal who owns an email address?

No. This is a reputation check, not an identity lookup. It never discloses personal information.

Can I detect disposable or temporary email addresses?

Yes. The domain check flags known disposable and temporary providers.

Can I check emails through the API?

Yes. The same verdict is available over the REST API and in bulk.
Explore

Related tools and pages.

Reported email addresses

Addresses that threat intelligence sources list for scam, phishing or spam, one report each.

Phone Checker

Scam phone number lookup

Domain Reputation

Full sender-domain analysis

URL Scanner

Check the links in the email

Sextortion email demanding bitcoin: what to do

A bluff sent in bulk: don’t pay or reply, change any password it quotes, report it.

Fake invoice or changed bank details: what to do before you pay

Call the supplier on a number you already had before paying any new bank details.
Research

Related articles from the research blog.

Blog post

Is Your Email Leaking Data? How to Check Email Reputation

Learn why email reputation matters for security and deliverability, and how to check if an email address is compromised or malicious.

Read more

Blog post

Email Authentication: Implementing DMARC, SPF, and DKIM for Email Security

Email spoofing enables phishing and business email compromise attacks. Learn how DMARC, SPF, and DKIM authentication protocols protect your domain from being impersonated in cyberattacks.

Read more

Blog post

Business Email Compromise: The Multi-Billion Dollar Threat

BEC attacks cost organizations billions annually through sophisticated impersonation and social engineering. Learn how domain spoofing detection and threat intelligence can protect your organization from CEO fraud and invoice scams.

Read more

Test it with your own indicators.

The free plan includes website lookups with no monthly cap and 250 API requests a month. Check the sources and limits, then connect the API.

Create free accountContact Sales

No credit card required · Free API key