Email Security Glossary
Definitions of the signals behind the VeriShield fraud score.
Canonical Email Normalization
The algorithmic process of reducing multiple variations of an email address (such as Gmail…
Shannon Entropy in Email Fraud Detection
An information-theory metric measured in bits per character that quantifies the randomness…
Disposable Email Address
A temporary, throwaway email address that expires after a short period or a set number of …
MX Record
A DNS Mail Exchanger record that specifies the mail servers responsible for accepting emai…
SPF (Sender Policy Framework)
A DNS TXT record that lists the IP addresses and hosts authorized to send email for a doma…
DMARC
Domain-based Message Authentication, Reporting and Conformance. A DNS policy that tells re…
DKIM
DomainKeys Identified Mail. An email authentication method that adds a cryptographic signa…
RDAP
Registration Data Access Protocol. The modern successor to WHOIS, used to query domain reg…
Domain Age
The time elapsed since a domain was first registered. Newly registered domains are statist…
Catch-All Email
A mail server configuration that accepts mail for any address at a domain, making it impos…
Hard Bounce
A permanent email delivery failure caused by an invalid, non-existent, or blocked address.…
Soft Bounce
A temporary email delivery failure such as a full mailbox or a transient server issue. Sof…
Email Deliverability
The ability of an email to reach the recipient inbox rather than being bounced or filtered…
Plus Addressing (Sub-addressing)
A feature where mail to user+tag@domain is delivered to user@domain. Abusers exploit it to…
Gmail Dot Trick
Gmail ignores dots in the local part, so j.o.h.n@gmail.com and john@gmail.com are the same…
Typo-Squatting
Registering domains that are common misspellings of popular domains (like gmial.com) to ca…
Fat-Finger Email Error
A user typo when entering an email address, such as hotmial.com instead of hotmail.com, le…
Levenshtein Distance
The minimum number of single-character edits needed to change one string into another. Use…
ASN (Autonomous System Number)
An identifier for a network on the internet. ASN lookup reveals whether a signup IP belong…
Datacenter IP
An IP address allocated to a hosting or cloud provider rather than a residential ISP. Huma…
OTP Bypass
Circumventing one-time-password verification, often by using disposable inboxes that auto-…
Multi-Accounting
Creating multiple accounts by the same person to abuse trials, coupons, or referrals, typi…
Fraud Score
A numeric risk rating, here 0-100, aggregating signals like disposability, entropy, domain…
SMTP Handshake
The conversation with a mail server (HELO, MAIL FROM, RCPT TO) used to probe whether a mai…