Email Glossary
Your comprehensive guide to email terminology. Learn about authentication, deliverability, infrastructure, and AI-powered email operations.
Authentication
Email security and verification protocols
ARC
ARC (Authenticated Received Chain) is an email authentication system that preserves authentication r...
BIMI
BIMI (Brand Indicators for Message Identification) is an email standard that displays your verified ...
DKIM
DomainKeys Identified Mail (DKIM) is an email authentication method that uses cryptographic signatur...
DMARC
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication p...
Domain Authentication
Domain authentication is the process of configuring DNS records (SPF, DKIM, DMARC) to prove to inbox...
Email Authentication
Email authentication is the process of verifying that an email was actually sent by the claimed send...
MTA-STS
MTA-STS (Mail Transfer Agent Strict Transport Security) is a security standard that enables email do...
SPF
Sender Policy Framework (SPF) is an email authentication method that specifies which mail servers ar...
Deliverability
Getting emails to the inbox
Allowlist
An allowlist (previously called whitelist) is a list of approved senders whose emails bypass spam fi...
Blocklist
A blocklist (previously called blacklist) is a database of IP addresses, domains, or senders identif...
Bounce Rate
Email bounce rate is the percentage of emails that couldn't be delivered to recipients, categorized ...
CAN-SPAM
CAN-SPAM is a U.S. law that sets rules for commercial email, establishing requirements for sender id...
Click-Through Rate
Click-through rate (CTR) is an email metric measuring the percentage of recipients who clicked a lin...
Email Deliverability
Email deliverability is the ability to successfully deliver emails to recipients' inboxes rather tha...
Email Throttling
Email throttling is the practice of limiting the rate at which emails are sent or accepted, used by ...
Email Validation
Email validation is the process of verifying that an email address is real, properly formatted, and ...
Feedback Loop
A feedback loop (FBL) is a service provided by inbox providers that notifies you when recipients mar...
GDPR for Email
GDPR (General Data Protection Regulation) is EU privacy legislation that affects email marketing by ...
Greylisting
Greylisting is a spam prevention technique that temporarily rejects emails from unknown senders, exp...
Hard Bounce
A hard bounce is a permanent email delivery failure that occurs when the recipient address is invali...
IP Warmup
IP warmup is the process of gradually increasing email volume from a new IP address to build sender ...
Open Rate
Open rate is an email metric showing the percentage of delivered emails that recipients opened, typi...
Preheader
A preheader is the preview text that appears after the subject line in email clients, providing addi...
Seed Testing
Seed testing (or inbox placement testing) involves sending emails to test addresses across major pro...
Sender Reputation
Sender reputation is a score assigned by inbox providers based on your sending history, determining ...
Soft Bounce
A soft bounce is a temporary email delivery failure caused by issues like a full mailbox, server dow...
Spam Trap
A spam trap is an email address used to identify spammers, either recycled from abandoned accounts o...
Suppression List
A suppression list is a database of email addresses that should not receive emails, including bounce...
Tracking Pixel
A tracking pixel is a tiny, invisible image embedded in emails that records when recipients open the...
Infrastructure
Email systems and protocols
DNS Records
DNS records for email are entries in your domain's DNS that configure mail delivery (MX), sender aut...
Email API
An email API (Application Programming Interface) allows developers to send, receive, and manage emai...
Email Service Provider (ESP)
An Email Service Provider (ESP) is a company that offers email sending infrastructure, tools, and se...
IMAP
IMAP (Internet Message Access Protocol) is a standard protocol for accessing email that keeps messag...
Message-ID
Message-ID is a unique identifier assigned to every email, used for threading conversations, trackin...
Multi-Tenant Email
Multi-tenant email is an architecture where a single email platform serves multiple customers (tenan...
MX Record
An MX (Mail Exchanger) record is a DNS record that specifies which mail servers are responsible for ...
Rate Limiting
Rate limiting is a technique that restricts the number of API requests or emails a sender can make w...
Return Path
The return path (also called envelope from or bounce address) is the email address where bounce noti...
Sending Domain
A sending domain is the domain used in the From address of emails, configured with DNS records to au...
SMTP
SMTP (Simple Mail Transfer Protocol) is the standard protocol for sending emails across the internet...
Tenant Isolation
Tenant isolation in email ensures that each customer's sending data — suppression lists, analytics, ...
Transactional Email
Transactional emails are automated messages triggered by user actions, such as password resets, orde...
Webhook
A webhook is an HTTP callback that sends real-time notifications to your application when specific e...
White Label Email
White label email is a service that lets platforms send email on behalf of their customers using the...
All Terms A-Z
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