26 articles.
Developers
What syntax, MX, disposable-domain and mailbox checks can tell you without sending mail, why SMTP probing gives false answers, and tested code in Node, Python and PHP.
11 min read
Fraud prevention
No public list ranks SMS pumping countries. How to sort destinations into allow, gate and block from published sources and your data, and which ranges to block.
12 min read
Fraud prevention
How silent network authentication (CAMARA Number Verification) and flash-call verification work, their coverage limits, and where pre-checks still help.
6 min read
Fraud prevention
OTP bombing floods a phone with codes from your send-code endpoint. A rate-limit recipe by number, IP, device and prefix, with pre-send checks.
7 min read
Guides
Phone validation checks the number; verification proves the user holds it. What each one stops, what they cost, and how to combine them in one flow.
7 min read
Guides
To check if a Yahoo email exists, send a test message and read the bounce, or run an account check in bulk. SMTP probes fail at Yahoo; here is why.
15 min read
Fraud prevention
You can check whether a Netflix, Amazon or Microsoft account uses a phone number (yes, no or unknown), but never see the account itself. How fraud teams use it.
10 min read
Fraud prevention
Free ways to run a phone number reputation lookup (regulator complaint data, phone labels, report sites), their limits, and when an API score is worth it.
10 min read
Fraud prevention
How promo abuse and multi-accounting work, which phone signals help, and friction tiers that stop repeat claims without punishing real customers.
7 min read
Guides
Check if a Gmail, Yahoo or Outlook account exists without sending mail: why SMTP probes fail at big providers, address aliases, bulk lists and privacy.
9 min read
Fraud prevention
How to tell if a phone number is fake at sign-up, in a lead form or on a list: format, line type, network status, app presence, reputation and patterns.
11 min read
Fraud prevention
Attackers change an account's phone number before resetting everything else. A checklist to secure the change-number flow without locking out real users.
7 min read
Guides
A Signal number lookup can only say whether a findable Signal account uses a number you hold, never whose it is. What the check sees and when not to use it.
7 min read
Fraud prevention
Why identity and messaging providers block voice and SMS codes as suspected toll fraud, what triggers it, and a pre-call check recipe for developers.
7 min read
Fraud prevention
Phone number reputation is a score built from complaints, reports and call patterns. Where the data comes from, what it can't tell you and how to use it fairly.
7 min read
Fraud prevention
Turn carrier, line type, network status and reputation signals into a phone number risk score with three outcomes, reason codes and calibrated thresholds.
8 min read
Developers
How AI agents check phone numbers and e-mail addresses safely: MCP server or function calling, which files an agent should read first, spend caps, and guardrails.
9 min read
Fraud prevention
IRSF is fraud where attackers trigger calls or texts to numbers they profit from. No free IRSF number database exists; use range lists and line-type checks.
8 min read
Fraud prevention
Before sending an OTP, look up the number: number type, line type and carrier, HLR status, porting. Which APIs offer it, what to compare, a pre-send flow.
10 min read
Guides
Mailbox validation says an address can receive mail. An account check says it is registered on a service. When to use each, and the privacy rules.
8 min read
Fraud prevention
A layered sign-up defence: format, line type, messaging presence, spam reputation and e-mail checks, mapped to friction tiers you can measure.
8 min read
Guides
A number's prefix shows the network its range was given to, not the one serving it today. How porting works, where lookups fail and how to handle it.
7 min read
Fraud prevention
A call-center workflow for routing inbound calls by spam reputation: levels, reasons, STIR/SHAKEN, limits of the data, and why no_reports isn't safe.
8 min read
Fraud prevention
What a SIM swap is, which SIM-swap data exists and who can get it, and which signals to combine before you trust an SMS code when that data is missing.
9 min read
Fraud prevention
Why VoIP numbers matter at sign-up, fixed vs non-fixed VoIP, which signals detect them, and how to add friction without turning away real customers.
8 min read
Fraud prevention
How SMS pumping (artificially inflated traffic) drains OTP budgets, the signals that give it away, and a layered checklist to stop it before you pay.
8 min read
