Questions & Answers
Practical answers to common email verification and anti-fraud questions.
How do I stop users from registering multiple accounts using Gmail dots and +plus aliases?
Normalize the local part before storing uniqueness: lowercase the address, replace @google…
How can I detect disposable email addresses at signup?
Match the domain against a maintained disposable blocklist and check for null MX records. …
What is a canonical email address?
A canonical email is the single standardized form of an address after removing provider-sp…
How do I block temp-mail and other temporary email services?
Block the known temp-mail domains and their rotating aliases, and verify MX records. Becau…
Why are disposable emails a fraud risk?
Disposable inboxes are untraceable, expire quickly, and require no identity, making them i…
How do I fix email typos like gmial.com or hotmial.com?
Use Levenshtein did-you-mean matching against popular domains and prompt the user to confi…
How does Shannon entropy detect bot email usernames?
Shannon entropy measures bits of randomness per character. Human usernames like john.doe h…
How can I check if an email address exists without sending mail?
Perform an SMTP handshake up to RCPT TO and read the server response, while respecting cat…
What is DMARC and why does it matter for verification?
DMARC tells receivers how to treat mail that fails SPF or DKIM. A domain with a strict p=r…
How do I reduce hard bounces in my email list?
Validate addresses at capture, correct typos with did-you-mean, suppress known invalid and…
Are dots really ignored in Gmail addresses?
Yes. Gmail treats j.o.h.n@gmail.com and john@gmail.com as the same mailbox. This is why do…
What is a catch-all domain and how do I handle it?
A catch-all domain accepts mail for any local part, so SMTP cannot confirm a specific mail…
How can I detect automated bot signups?
Combine high-entropy username detection, datacenter/VPN ASN checks, disposable domain bloc…
How does domain age relate to fraud?
Domains registered very recently are statistically more likely to be created for abuse. Li…
How do I stop users from abusing free trials with multiple accounts?
Deduplicate by canonical email hash, block disposable domains, and flag high-entropy or da…
What is plus addressing and is it legitimate?
Plus addressing (user+tag@domain) is a legitimate filtering feature, but it is also abused…
How do I verify emails in real time without slowing signup?
Call a low-latency edge verification API during signup. VeriShield Edge runs on Cloudflare…
What is an MX record and what does a null MX mean?
An MX record lists the servers that accept mail for a domain. A null or missing MX means t…
How do I prevent referral program fraud?
Hash the canonical email to deduplicate referrers, block disposable domains, and score ent…
What is email deliverability and how is it measured?
Deliverability is the rate at which mail reaches the inbox. It is influenced by sender rep…
How do I block Mailinator and similar public inboxes?
Block mailinator.com and its alternate domains, and detect the public-inbox pattern. VeriS…
What does a 0-100 email fraud score mean?
It aggregates disposability, entropy, domain age, IP reputation, and authentication into o…
How do I normalize googlemail.com addresses?
Replace @googlemail.com with @gmail.com, then apply Gmail dot and plus normalization. Both…
How do I detect datacenter or VPN IPs at signup?
Look up the IP ASN and classify it as datacenter, VPN, or residential. Human signups rarel…