Glossary
Email glossary
Plain definitions of 79 terms from email marketing, deliverability and verification.
- Authentication
- Compliance
- DNS
- Deliverability
- Email marketing
- General
- Infrastructure
- Metrics
- Security
- Verification
A record
A DNS record that maps a domain name to an IPv4 address.
DNS
Abuse complaint
When a recipient marks an email as spam or junk, generating a complaint to the sender's email provider.
Deliverability
Accept-all domain
See catch-all domain. A mail server configured to accept emails sent to any address at that domain.
Verification
Backscatter
Bounce messages sent to forged sender addresses, often caused by spam or viruses using fake return addresses.
Deliverability
Blacklist
A database of IP addresses or domains identified as sources of spam. Also called blocklist or DNSBL.
Deliverability
Blocklist
See Blacklist. A list of IPs or domains blocked due to spam or malicious activity.
Deliverability
Bounce
An email that cannot be delivered and is returned to the sender with an error message.
Deliverability
Bounce rate
The percentage of sent emails that could not be delivered. Calculated as (bounced emails / sent emails) × 100.
Metrics
CAN-SPAM Act
US law establishing requirements for commercial email, including opt-out mechanisms and sender identification.
Compliance
Catch-all domain
A mail server configured to accept emails to any address at the domain, making individual mailbox verification impossible.
Verification
Click-through rate (CTR)
The percentage of email recipients who clicked on one or more links in an email.
Metrics
Cold email
An unsolicited email sent to a recipient without prior contact or relationship.
Email marketing
Complaint rate
The percentage of recipients who mark your email as spam. Should be kept below 0.1%.
Metrics
Dedicated IP
An IP address used exclusively by one sender, giving full control over sender reputation.
Infrastructure
Deliverability
The ability of an email to reach the recipient's inbox rather than being blocked or filtered to spam.
Deliverability
Disposable email
A temporary email address created for short-term use, often to avoid spam or hide identity.
Verification
DKIM
DomainKeys Identified Mail. An email authentication method using cryptographic signatures to verify sender identity.
Authentication
DMARC
Domain-based Message Authentication, Reporting & Conformance. A policy framework building on SPF and DKIM.
Authentication
DNS
Domain Name System. The internet's phone book that translates domain names to IP addresses.
DNS
DNSBL
DNS-based Blackhole List. A blacklist queryable via DNS to check if an IP is flagged for spam.
Deliverability
Domain reputation
A score assigned to a sending domain based on email engagement, complaints, and sending practices.
Deliverability
Double opt-in
A subscription process requiring users to confirm their email address by clicking a verification link.
Compliance
Email authentication
Technical methods (SPF, DKIM, DMARC) to verify that an email comes from its claimed sender.
Authentication
Email client
Software used to read, send, and manage emails (e.g., Gmail, Outlook, Apple Mail).
General
Email header
Metadata at the top of an email containing routing information, sender details, and authentication results.
General
Email hygiene
The practice of maintaining a clean email list by removing invalid, inactive, and risky addresses.
Verification
Email service provider (ESP)
A company that provides email marketing and sending services (e.g., Mailchimp, SendGrid, Klaviyo).
Infrastructure
Email verification
The process of validating that an email address exists, is properly formatted, and can receive messages.
Verification
Email warmup
Gradually increasing email sending volume on a new IP or domain to build sender reputation.
Deliverability
Engagement rate
A metric measuring how recipients interact with emails through opens, clicks, and replies.
Metrics
Envelope sender
The email address used in the SMTP conversation, which may differ from the visible "From" address.
General
GDPR
General Data Protection Regulation. EU law governing data privacy and consent for email marketing.
Compliance
Graymail
Legitimate email that recipients signed up for but no longer engage with, often filtered or ignored.
Deliverability
Greylisting
An anti-spam technique that temporarily rejects emails from unknown senders, expecting legitimate servers to retry.
Deliverability
Hard bounce
A permanent delivery failure, typically because the email address doesn't exist or the domain is invalid.
Deliverability
Header
See email header. The metadata portion of an email containing routing and authentication information.
General
Honeypot
A type of spam trap - an email address created specifically to catch spammers harvesting addresses.
Deliverability
IMAP
Internet Message Access Protocol. A protocol for retrieving emails from a server while keeping them stored remotely.
Infrastructure
Inbox placement
Whether an email lands in the primary inbox, promotions tab, or spam folder. Kawaa inbox placement testing is coming soon.
Deliverability
IP reputation
A score assigned to an IP address based on its email sending history and recipient engagement.
Deliverability
IP warmup
The process of gradually increasing sending volume from a new IP address to establish reputation.
Deliverability
ISP
Internet Service Provider. In email context, often refers to mailbox providers like Gmail, Yahoo, and Microsoft.
Infrastructure
Mail transfer agent (MTA)
Software that transfers emails between servers using SMTP protocol.
Infrastructure
Mailbox provider
A service that hosts email accounts and manages inbox delivery (e.g., Gmail, Outlook, Yahoo).
Infrastructure
MIME
Multipurpose Internet Mail Extensions. A standard for formatting non-text email content like attachments and HTML.
General
MX record
Mail Exchange record. A DNS record specifying the mail server responsible for receiving email for a domain.
DNS
Open rate
The percentage of delivered emails that were opened by recipients.
Metrics
Opt-in
When a user gives explicit permission to receive emails, typically by subscribing to a list.
Compliance
Opt-out
When a user withdraws permission to receive emails, typically by clicking an unsubscribe link.
Compliance
Phishing
Fraudulent emails designed to trick recipients into revealing sensitive information or clicking malicious links.
Security
POP3
Post Office Protocol version 3. A protocol for downloading emails from a server to a local device.
Infrastructure
Pristine spam trap
An email address that was never used for legitimate purposes, created solely to catch spammers.
Deliverability
Recycled spam trap
A previously valid email address repurposed as a spam trap after being abandoned for an extended period.
Deliverability
Return path
The email address where bounce notifications are sent. Used in SPF authentication.
General
Role-based email
An email address associated with a function rather than a person (e.g., info@, support@, sales@).
Verification
Sender Policy Framework
See SPF. An email authentication protocol that specifies which servers can send email for a domain.
Authentication
Sender reputation
A score reflecting the trustworthiness of an email sender based on sending practices and engagement.
Deliverability
Sender Score
A reputation rating from 0-100 assigned to sending IP addresses, provided by Validity (formerly Return Path).
Deliverability
Shared IP
An IP address used by multiple senders, where reputation is influenced by all users' behavior.
Infrastructure
Single opt-in
A subscription process where users are added to a list immediately after submitting their email, without confirmation.
Compliance
SMTP
Simple Mail Transfer Protocol. The standard protocol for sending emails between servers.
Infrastructure
Soft bounce
A temporary delivery failure, often due to a full mailbox, server issues, or message size limits.
Deliverability
Spam
Unsolicited bulk email, typically commercial in nature, sent without recipient consent.
General
Spam filter
Software that analyzes emails to identify and block spam from reaching the inbox.
Deliverability
Spam trap
An email address used to identify spammers. Includes pristine traps, recycled traps, and typo traps.
Deliverability
SPF
Sender Policy Framework. A DNS-based email authentication method listing authorized sending servers for a domain.
Authentication
Spoofing
Forging email headers to make a message appear to come from a different sender than the actual source.
Security
Sunsetting
The practice of removing unengaged subscribers from email lists to maintain list quality and sender reputation.
Email marketing
Syntax validation
Checking if an email address follows the correct format (e.g., user@domain.com) according to RFC standards.
Verification
Throttling
Rate limiting email sending speed to avoid overwhelming receiving servers or triggering spam filters.
Deliverability
TLS
Transport Layer Security. Encryption protocol securing email transmission between servers.
Security
Transactional email
Automated emails triggered by user actions (e.g., order confirmations, password resets, notifications).
Email marketing
Typo trap
A spam trap based on common misspellings of popular domains (e.g., gmial.com instead of gmail.com).
Deliverability
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