Email Marketing Glossary

A/B Split Test

Also known as: Split Test, Test

An A/B split test is when you send two versions of an email to different groups to see which one gets better results. You change one thing at a time and then pick the version that performs best.

Abandoned Cart Email

Also known as: Cart Abandonment Email, Cart Recovery Email

An automated email that goes out when someone adds items to their cart but leaves without buying. These emails show what they left behind and usually include a direct link back to their cart. Most businesses send a series of 2-3 reminders over a few days, sometimes sweetening the deal with a discount or free shipping offer.

Acceptable Use Policy

Also known as: AUP

An Acceptable Use Policy (AUP) is a set of rules defined by an ESP or ISP that governs what type of content and behavior is allowed on their network.

Accessibility

Making your emails easy to read and use for everyone, including people with disabilities. It covers things like clear layout, readable text, helpful alt text, and strong color contrast.

Alternative Text

Also known as: Alt Text, Descriptive Text

Short text that explains what an image shows and why it is in your email. It helps people and email clients understand your message when the image does not load.

AMP

Also known as: AMP Email, AMP4Email, Accelerated Mobile Pages, ⚡️

AMP is a Google tech that makes emails interactive, so people can do things like submit forms or browse products without leaving the inbox. It only works in a few email clients, so you always need a normal HTML fallback.

AMPscript

AMPscript is Salesforce Marketing Cloud's scripting language for personalizing each email with data from your subscriber records. It runs at send time so every person gets content that matches their details and behavior.

Analytics

The practice of tracking what happens after you hit send on your email campaigns. Analytics shows you who opened, who clicked, who bought, and who bounced—turning guesswork into data-driven decisions about what's actually working in your email program.

Animated GIF

Also known as: GIF, JIF

An animated GIF is a short, looping image that feels like a tiny video in an email. It starts playing as soon as the email opens and works in most inboxes without extra clicks.

API

Also known as: Application Programming Interface

A way for different software tools to talk to each other. In email marketing, APIs let your website, app, and email platform share data automatically so information stays in sync without extra work.

Approval

The formal sign off from the people who must review your email before it goes out. It is the step where stakeholders confirm the content is correct, safe, and on brand.

Attachment

A file that travels with an email message, like a PDF or image. Attachments are fine for one-to-one emails but risky for bulk marketing sends because they can hurt deliverability.

Attribution

Attribution is how you connect revenue or signups back to the emails and touchpoints that helped cause them. It helps you see which campaigns actually drive results so you can spend time and budget on what works.

Authenticated Received Chain (ARC)

Also known as: ARC, Email ARC

Authenticated Received Chain (ARC) is an email standard that keeps your authentication results when a message is forwarded or passes through mailing lists. It lets receiving servers see that earlier checks passed even if SPF or DKIM now look broken.

Authentication

The process of proving to inbox providers that your emails really come from your domain. It helps stop spoofing and keeps more of your messages out of spam.

Autoresponder

Also known as: Out of Office, OOO, Auto-reply

An autoresponder is an automatic email that sends right after someone takes an action, like emailing you or filling out a form. It confirms what they did and tells them what will happen next.

Average Order Value (AOV)

Also known as: AOV, Average Transaction Value

Average order value is the average amount a customer spends on each order. You calculate it by dividing total revenue by the number of orders.

Backscatter

Also known as: Blowback, collateral spam

Backscatter is when a mail server sends bounce messages to an innocent third party because their email address was spoofed by a spammer.

Batch Email

Also known as: Batch Send, Bulk Send

Batch email is when you send the same email to many people at once. Your email platform sends it in groups so you can reach a large list without hurting deliverability.

Behavioral Targeting

Also known as: Behavior-Based Targeting, Action-Based Targeting

Behavioral targeting means sending emails based on what people do, not just who they are. You use actions like pages visited, products viewed, and purchases to decide which message to send next.

Behavioral Trigger

Also known as: Behavior-Based Trigger, Action Trigger

An automated email that sends when someone does something specific on your site or in your product. It reacts to real behavior so the message matches what they just did.

BIMI

Brand Indicators for Message Identification (BIMI) lets your verified logo appear next to your emails in inboxes that support it. It gives people a clear visual signal that the message really comes from your brand.

Blacklist

Also known as: Blocklist, Denylist

An email blacklist is a list of IP addresses or domains that inbox providers treat as unsafe. If you are on one, your emails are more likely to land in spam or get blocked before they arrive.

Blast

Also known as: Campaign, Send

An old term for sending one bulk email to many people at once. It often suggests a generic, untargeted message instead of a thoughtful campaign.

Blocklist

Also known as: Blacklist

A blocklist is a list of IP addresses or domains that are known for sending bad or unwanted email. If you are on a blocklist, inbox providers often block or filter your messages before anyone can see them.

Bounce (Hard)

Hard bounce is when an email cannot be delivered because the address is invalid or blocked. It is a permanent failure and the address should be removed from your list.

Bounce (Soft)

A soft bounce is when an email fails to deliver for a temporary reason, like a full inbox or a short outage at the recipient mail server. The address is still valid, and the email may be delivered if you try again later.

Bounce Rate

Also known as: Email Bounce Rate

Bounce rate is the percentage of emails that could not be delivered to recipients. It shows how many addresses are invalid or blocked compared to the total you tried to send.

Branching

Also known as: Workflow Branching, Path Branching

Branching is when an automation splits into different paths based on a person's data or actions. It sends people into different email flows so messages feel more relevant.

Broadcast

Also known as: Broadcast Email, Mass Email

A one time email you send to your whole list or a segment at a single time. You write it once, choose who should get it, and it sends when you press send.

Browse Abandonment

Also known as: Browse Abandonment Email, Product View Abandonment

Browse abandonment is when someone views products on your site but leaves without adding anything to their cart or buying. A browse abandonment email is an automated follow up that reminds them what they saw and invites them back.

Bulk Mail

Also known as: Bulk Marketing, Blast

Bulk mail is sending one email to a large group of people at the same time, usually without segmentation or deep personalization. It is a simple way to reach many subscribers with one message.

California Consumer Privacy Act (CCPA)

Also known as: CCPA

A California privacy law that gives residents clear rights over how businesses collect, use, and share their personal data. It applies to larger companies and those that handle a lot of data from people who live in California.

Call-To-Action (CTA)

Also known as: CTA

The button or link in your email that tells people exactly what to do next. Usually short, direct text like "Shop now" or "Start my free trial" that makes the next step clear.

Campaign

Also known as: Email Campaign, Marketing Campaign

A campaign is a planned set of emails that work together toward one clear goal. Each email supports the same outcome and is sent to a defined audience over a set period.

CAN-SPAM

CAN-SPAM is the main email marketing law in the United States. It sets the basic rules for how you can send commercial email and how people can opt out.

CASL

Canada's Anti-Spam Legislation. It sets clear rules for how you collect consent and send marketing emails to people in Canada.

Catch-All

Also known as: Accept-all

A catch-all is a server configuration that accepts emails sent to any address at a domain, even if the specific mailbox doesn't exist.

Click Rate (CR)

Also known as: Click Through Rate, CR

The percentage of delivered emails where someone clicks a link. It shows how many people take action from your email.

Click To Open Rate (CTOR)

Also known as: CTOR

The percentage of people who opened your email and then clicked a link inside. It shows how engaging your content is after someone opens.

Click-Through Rate (CTR)

Also known as: CTR, Click Rate

Percentage of delivered emails where someone clicked a link. It is a simple way to see how many people move from reading your email to taking action.

Complaint

Also known as: Spam Complaint

When someone clicks the spam or junk button on your email instead of unsubscribing. That action tells inbox providers your email was unwanted and counts as a complaint against your sending reputation.

Complaint Rate

Also known as: Spam Complaint Rate, Abuse Rate

The percentage of people who mark your emails as spam. It shows how many subscribers see your message as unwanted and affects whether future emails reach the inbox.

Conditional Logic

Also known as: If/Then Logic, Branching Logic

Conditional logic is the if/then rules in your email automation that choose what to send based on what each person does or does not do. It helps you send different emails to people in the same flow so each message feels more relevant.

Consent

Also known as: Permission

Clear permission someone gives you to send them email. It means they understand what they signed up for and have agreed to get messages from you.

Conversion Goal

Also known as: Goal, Automation Goal, Workflow Goal

A conversion goal is the action you want someone to take after your email. It shows that your automation did its job and led to a clear result you can track.

Cost Per Mile (CPM)

Also known as: Cost Per Mile, Cost Per Thousand, CPT

CPM is what you pay to send 1,000 emails through a provider. It shows your cost per thousand sends so you can compare pricing between tools.

CSS

Also known as: Cascading Style Sheets

CSS is the styling code that controls how your emails look, including fonts, colors, spacing, and layout.

Customer Acquisition Cost (CAC)

Also known as: CAC

The average amount you spend to win one new paying customer. It includes your marketing, sales, and related costs over a period divided by how many new customers you gained.

Customer Journey

Also known as: Journey, User Journey, Email Journey

A customer journey is the path someone takes from first hearing about your brand to becoming a repeat buyer. In email marketing, it is the series of emails and touch points they receive over time.

Customer Lifetime Value (CLV)

Also known as: CLV, LTV, Lifetime Value

The total money a customer is expected to spend with your business from their first purchase until they stop buying. It helps you decide how much you can afford to spend to win that customer and keep them coming back.

Dark Mode

Dark mode is a display setting where email apps switch light backgrounds to dark ones and flip text colors so emails feel easier to read in low light.

Data Retention

Also known as: Data Retention Policy, Retention Period

How long you keep customer and email data before you delete it. It sets clear rules for when you remove or anonymize contact and activity data so you only hold what you actually need.

Dedicated IP

Also known as: Dedicated Server

An IP address used only by your business to send email. It helps higher volume senders control their own reputation instead of sharing it with others.

Dedicated Server

Also known as: Dedicated IP

A dedicated server is a private email server with its own IP address that only your company uses to send email. It gives you direct control over your sender reputation and delivery results.

Deferral

Also known as: Temporary failure, 4xx error, soft bounce

A deferral is when a receiving email server temporarily refuses a message but suggests trying again later.

Deliverability

Also known as: Email Deliverability, Inbox Placement

Deliverability is how often your emails land in the inbox instead of spam or getting blocked. Strong deliverability means people actually see what you send and can act on it.

Delivery Rate (DR)

Also known as: DR

Delivery rate is the percentage of emails that are accepted by recipients' mail servers without bouncing. It shows how many of your sent emails clear the technical checks so they can be placed in a mailbox.

Design System

A design system is a shared set of reusable email building blocks and rules your team uses to create emails. It keeps layouts, styles, and code consistent so you can build emails faster.

Disposable Email

Also known as: Burner email, throwaway address

A disposable email is a temporary address created for a single use, often to sign up for a service without revealing a real address.

DKIM

Also known as: DomainKeys Identified Mail

DKIM is a way to sign your emails so receiving servers can confirm they came from your domain and were not changed on the way.

DMARC

Also known as: Domain-based Message Authentication Reporting and Conformance

DMARC is an email security policy that tells receiving mail servers what to do when messages from your domain fail SPF or DKIM checks. It helps stop spoofing and gives you reports about who is sending email using your domain.

Domain Reputation

How trusted your sending domain is by email providers like Gmail and Outlook. A strong domain reputation keeps your emails in the inbox instead of spam.

Double Opt-In

Also known as: Confirmed Opt-In, COI

When someone signs up, you send a confirmation email and only add them after they click the link. It adds a small extra step but keeps your list clean and engaged.

Drip Campaign

Also known as: Drip Sequence, Email Drip, Automated Sequence

A series of pre-written emails that automatically go out over time, like a slow drip from a faucet. You write them once, set the schedule, and they nurture leads on autopilot. Someone signs up today, they get email 1. Three days later, email 2. A week later, email 3. Perfect for welcoming new subscribers, educating prospects, or onboarding customers without lifting a finger.

Dynamic Content

Also known as: Live Content, Real-time Content

Dynamic content is email content that updates based on who is viewing it or when they open it. It can pull in data like products, offers, or status in real time so one email feels tailored to each person.

Email Alias

Also known as: Plus Alias

An email alias is a version of your email address that still delivers to the same inbox. It lets you create different addresses for signups and tracking without managing more accounts.

Email Appending

Email appending is when you use a third party to add email addresses to your existing customer records based on other details like name or postal address. It is risky because these people did not ask to hear from you, which often leads to spam complaints and poor deliverability.

Email Client

Also known as: Email Program, Email App, Client

Software or apps people use to read, send, and manage email, such as Gmail or Apple Mail. Different email clients can display the same email in different ways, which affects how your emails look and perform.

Email Engagement Score

Also known as: Engagement Score, Subscriber Engagement Score

A simple score that shows how active a subscriber is with your emails, based on actions like opens, clicks, replies, and purchases. It helps you quickly see who is engaged and who might be slipping away.

Email Geek

An email geek is someone who loves the craft of email and works to make every send better. They test ideas, care about deliverability, and treat subscribers like real people, not just numbers on a list.

Email Header

Also known as: Message Header, Email Metadata

An email header is the technical information attached to every email that shows where it came from and how it moved between servers. It also records checks that help decide whether the message is safe and legitimate.

Email Marketing

Email marketing is the practice of sending emails to groups of people to build relationships and drive actions like sales or sign ups.

Email Sequence

Also known as: Email Series, Message Sequence

An email sequence is a planned set of emails that send automatically after someone takes a specific action, like signing up or buying. It helps you guide subscribers through a simple journey without sending every email by hand.

Email Service Provider (ESP)

Also known as: ESP, Email Platform, Marketing Automation Platform

The software you use to send and manage email campaigns. It stores your contacts, sends messages in bulk, and tracks what happens after you hit send.

Emoji

Small icons like 😊 or 🎉 that you add to subject lines and email copy so your message is easier to notice and understand. They act as simple visual cues that show tone and make your emails feel more personal.

Engagement

The actions people take with your emails, like opens, clicks, replies, forwards, and time spent reading. Strong engagement shows that your audience is paying attention and wants to hear from you.

Engagement Rate

Also known as: Email Engagement Rate, Overall Engagement

The share of your email subscribers who interact with what you send through opens, clicks, replies, or other actions. It gives you a quick read on how healthy and relevant your email program is.

Envelope

The email envelope is everything someone sees about your email in their inbox before they open it. It includes the sender name, subject line, and preview text that guide their choice to open or ignore it.

Event Trigger

Also known as: Trigger, Automation Trigger

A specific action or change that tells your email system to start an automation. It can be a sign up, a purchase, a page view, or a data update that kicks off a workflow.

Feedback Loop (FBL)

Also known as: FBL, Complaint Feedback Loop

A feedback loop is a system where inbox providers tell you when someone marks your emails as spam. It gives you a clear signal so you can remove complainers fast and protect your sender reputation.

Forward

Also known as: Forward To A Friend, FTAF

When someone shares your email with another person by clicking forward in their email client or using a forward to a friend link in your email. It is a strong signal that they found your message useful, but manual forwards often break tracking so many teams prefer using dedicated forward to a friend features instead.

Forward Rate

Also known as: Share Rate, Email Forward Rate

Forward rate is the percentage of delivered emails that people share or forward to others. It shows how many subscribers liked your email enough to pass it on.

From Address

Also known as: From Field, Sender Address

The email address people see as the sender in their inbox. It tells them who the message is from and helps them decide whether to open it.

Funnel

A funnel is the path someone follows from first hearing about you to becoming a customer. It breaks that journey into stages so you can send the right email at the right time.

GDPR

The General Data Protection Regulation is Europe's privacy law that sets rules for how you collect, store, and use personal data from people in the EU. It shapes how you build email lists, send marketing messages, and handle requests about data access or deletion.

Google Postmaster Tools

Also known as: GPT

Google Postmaster Tools is a free dashboard provided by Gmail that shows senders data about their domain reputation, spam rate, and authentication.

Greylisting

Greylisting is an anti-spam technique where a receiving server temporarily rejects emails from unknown senders to test if they are legitimate.

HELO/EHLO

HELO and EHLO are the commands a sending server uses to identify itself at the start of an SMTP conversation.

Honey Pot

A honey pot is a fake email address used by inbox providers and anti spam groups to spot senders with bad list practices. Sending to these addresses hurts your reputation and makes it harder for your emails to reach the inbox.

HTML

HTML is the code that shapes how your email looks and feels in the inbox. In email marketing it uses a simpler, stricter version of web HTML so your design works across many different clients.

Image Blocking

When email clients stop images from loading automatically, so people see empty boxes or alt text instead of pictures. This protects users from tracking and unsafe content, so you should never rely only on images to tell your message.

Inbox Placement Rate

Also known as: IPR, Inbox Rate, Delivery Rate

Inbox placement rate is the percentage of your sent emails that land in the inbox instead of spam or getting blocked. It shows how often your messages actually reach people.

Inclusion

Making your emails easy to understand and use for many different people. It means thinking about language, images, and layout so more people feel welcome and able to take action.

Integration

Connecting your email platform to other tools so data moves between them and can trigger emails at the right time.

Internet Service Provider

Also known as: ISP

Companies that provide internet access and often email services to people and businesses. In email marketing, they decide if your emails reach the inbox or land in spam.

IP Warming

Also known as: Server Warming

IP warming is the process of slowly increasing email volume from a new IP so inbox providers learn to trust it. You start with small sends to engaged contacts and raise the volume over a few weeks.

Kinetic Email

Also known as: Interactive Email

Kinetic email is an interactive email that lets people click, swipe, or tap inside the message instead of going to a web page. It uses HTML and CSS to create simple actions like carousels, accordions, or quick surveys right in the inbox.

Lead Scoring

Also known as: Lead Score, Prospect Scoring

Lead scoring ranks your leads by how interested and ready to buy they seem based on simple scores from their actions. It helps you see warm leads fast so you can focus your time where it makes the most sense.

List

Also known as: Audience, Segment

Your email list is the group of people who have asked to hear from you by email. It is an audience you own and can contact any time without relying on ads or social platforms.

List Broker

Also known as: List Dealers, Spammers

Companies or people who sell or rent email lists to marketers. Buying from them is risky because contacts never asked to hear from you and you can hurt deliverability or break the law.

List Churn

Also known as: Churn

The percentage of subscribers you lose from your email list in a set time period. It includes people who unsubscribe, mark you as spam, or are removed because their address no longer works.

List Fatigue

List fatigue is when your email subscribers tune out because they see too many emails or content that does not feel useful. They stop opening, clicking, and buying, which hurts your results over time.

List Growth Rate

Also known as: Email List Growth, Subscriber Growth Rate

The speed your email list grows or shrinks over time, shown as a percentage. It includes both new subscribers and people who leave, so you see your real list change.

List Hygiene

List hygiene is the practice of cleaning your email list by removing bad or inactive addresses. It keeps your list focused on people who still want your emails.

List-Unsubscribe

Also known as: One-click unsubscribe

List-Unsubscribe is an email header that allows recipients to unsubscribe from a mailing list without searching for a link in the footer.

Localization

Making your emails feel natural in different countries and cultures. You adjust language and key details so each audience feels the message was made for them.

Mail Loop

Also known as: Routing loop

A mail loop occurs when an email is forwarded back and forth between servers without ever reaching a final destination.

Marketing Automation

Marketing automation uses rules and triggers to send emails based on what people do. It saves time and keeps your messages timely and relevant.

Marketing Automation Platform (MAP)

Also known as: MAP

Software that helps you send the right messages to people based on what they do. It automates emails and other marketing tasks so you do not have to do them by hand.

MarTech

Also known as: Marketing Technology

The tools and software you use to plan, run, and track your marketing across channels. It covers everything from email platforms to analytics and CRM so your work is connected instead of scattered.

Message Transfer Agent (MTA)

Also known as: MTA, Mail Transfer Agent, Mail Server

A Message Transfer Agent is the server that moves email from one mail system to another. It takes outgoing messages from your email tool and hands them off to the next mail server using SMTP until they reach the right inbox.

Metrics

Email metrics are the numbers that show how your campaigns perform. They make it clear how many people open, click, and buy from your emails.

MIME Type

Also known as: MIME

MIME types are labels that tell email clients what kind of content each part of a message holds. They make sure text, HTML, images, and attachments show up the way you expect.

MTA-STS

Also known as: Mail Transfer Agent Strict Transport Security

MTA-STS is a security standard that allows a domain to force authentication and encryption for inbound emails.

Multi-Touch Attribution

Also known as: MTA, Attribution Modeling

Multi-touch attribution tracks all the marketing touches that lead to a sale and shares credit between them. It shows the full path a customer takes instead of only the first or last click.

Multivariate Test

Testing different versions of several email elements at the same time to find the best mix. Instead of changing only one thing, you compare full combinations to see which gets the most opens, clicks, or sales.

Newsletter

Also known as: Email Newsletter, Regular Newsletter

An email newsletter is a regular email you send to subscribers with updates, ideas, and useful content. It keeps a steady connection with your audience between launches or promotions.

Nurture

Nurture means building a relationship with people on your list through helpful, well timed emails. The goal is to move them closer to buying while keeping existing customers active and happy.

Omnichannel

Omnichannel means your customer experience feels joined up across email, your site, ads, and support, so every touchpoint shares the same view of the customer. It uses shared data to keep messages consistent and relevant no matter where someone interacts with you.

Onboarding

Also known as: Welcome Series

The emails you send to new subscribers or customers in their first days with you. Onboarding sequences welcome them, show what they can do next, and help them get value fast.

Open Rate (OR)

The percentage of delivered emails that people open. Useful as a quick health check on subject lines and inbox placement, but it does not show real engagement on its own.

Open Relay

Also known as: Insecure relay

An open relay is an email server configured to allow anyone on the internet to send email through it, regardless of who they are.

Opt-Out

An opt-out is when someone on your email list chooses to stop getting your emails and uses a clear way to unsubscribe or change their settings. You must respect this choice quickly to stay compliant and protect your sender reputation.

Personalization

Personalization means tailoring your emails to each person based on what you know about them. You use details like their name, past purchases, and behavior so your emails feel relevant instead of generic.

Plain Text

Plain text emails contain only text without images, buttons, or design, so they look like a normal personal message. They are simple to create and often feel more authentic, but you give up detailed tracking and visual branding.

Post-Purchase Email

Also known as: Post-Purchase Follow-Up, Order Confirmation Follow-Up

The series of emails you send customers after a purchase to confirm the order, share updates, and support them after they buy.

Preference Center

Also known as: Preferences Page, Unsubscribe Page

A preference center is a simple page where subscribers choose which emails they still want to get from you. It lets people change topics or frequency instead of leaving your list completely.

Preview Text

Also known as: Preheader Text

Short line of copy that appears next to or under your subject line in the inbox. Usually pulled from the email body and used to give people a reason to open.

Privacy and Electronic Communications Regulations (PECR)

Also known as: PECR, UK PECR

PECR is the UK law that covers email, SMS, calls, and other digital marketing. It sets clear rules for consent, marketing messages, cookies, and other tracking.

Privacy Policy

Also known as: Privacy Notice, Data Protection Policy

Your privacy policy explains what data you collect from people, how you use it, and how you keep it safe. It sets clear expectations so subscribers know what happens when they share their email and other details with you.

Promotions Tab

Also known as: Promo Tab, Promotions Folder

The Promotions tab is the place in Gmail where most marketing and sales emails appear. It keeps discounts, offers, and brand updates in one spot so people can check them when they want to shop.

PTR Record

Also known as: Pointer record

A PTR record is a type of DNS record that maps an IP address to a domain name, used for Reverse DNS.

QA

Also known as: Testing, Approvals

Quality Assurance for email. It is the process of checking each campaign before you send it so you catch mistakes early.

Recency, Frequency, Monetary (RFM)

RFM is a way to score customers based on how recently they bought, how often they buy, and how much they spend. It helps you spot your best customers quickly and see who might be slipping away.

Reengagement

Also known as: Win Back

Reengagement is the process of running a short email campaign to people who stopped opening or clicking your emails. The goal is to either win them back or remove them cleanly from your list.

Reply-To

Also known as: Reply To Address

The email address where replies to your message are sent. It can be different from the From address so replies land with the right person or team.

Reputation

Also known as: Sender Reputation

Sender reputation is the trust score mailbox providers give your emails based on how you send and how people react. It helps decide if your messages land in the inbox or get pushed to spam.

Responsive Email

An email design that adjusts to any screen size so it stays easy to read and click on phones, tablets, and desktops.

Retention

Retention is how well you keep customers coming back after their first purchase. It is about staying in touch so they stay active, buy again, and do not churn.

Return-Path

Also known as: Bounce Address, Envelope From

The technical email address that collects bounces and delivery failure notices. It is separate from the visible From address and helps mail servers track delivery issues and clean up bad addresses.

Revenue Per Email Sent (RPE)

Also known as: RPE

Revenue Per Email Sent (RPE) tells you how much money you make on average from each email you send. You find it by dividing the money from a campaign by the number of emails sent.

Reverse DNS

Also known as: rDNS, FCrDNS

Reverse DNS is the process of resolving an IP address back to a domain name, the opposite of standard DNS lookup.

Role Account

Also known as: Role-based email, functional address

A role account is an email address managed by a job function or a group rather than a specific person, such as admin@ or support@.

Safelist

Also known as: Whitelist, Safe Sender List

A safelist is a list of email addresses or domains that a person marks as trusted so their emails skip spam filters and go straight to the inbox. It tells the email provider to treat those messages as safe and deliver them to the main inbox.

Seed List

Also known as: Seed Addresses, Test Inboxes

A seed list is a small group of test email addresses you add to campaigns so you can see if messages land in the inbox, spam, or other folders before you send to your full list.

Segmentation

Also known as: Segment, Group

Segmentation means splitting your email list into smaller groups so you can send messages that match what each group cares about. It helps you talk to the right people instead of blasting the same email to everyone.

Send Time Optimization

Also known as: STO, Optimal Send Time, Best Time to Send

A feature that chooses the best time to send each email based on when a person usually opens and clicks your messages.

Sender Score

Sender Score is a 0 to 100 rating of your sending reputation. A higher score means inbox providers are more likely to trust your emails and keep them out of spam.

Shared IP

Also known as: Shared Server

A shared IP is an IP address that many companies use to send email. Your messages go out from the same address as other senders on your platform, so your reputation is linked to how that group behaves.

Shared Server

Also known as: Shared IP

A shared server is an email server and IP address that many companies use to send their emails. Your messages go out from the same place as other senders, so you share the same reputation.

Single Opt-In

Single opt-in is when someone joins your email list with one simple step. They fill out a form, hit submit, and start getting your emails right away.

Smart Host

Also known as: Relay host, smarthost

A smart host is an intermediate mail server that relays email on behalf of another server, often to improve deliverability.

SMTP

SMTP (Simple Mail Transfer Protocol) is the standard way email servers send messages to each other. It handles the handoff from your email tool to the recipient's mail server so messages can land in the inbox.

SMTP Banner

Also known as: Service banner

The SMTP banner is the initial text greeting a mail server sends when a connection is first established.

SNDS

Also known as: Smart Network Data Services

SNDS is a reputation monitoring portal provided by Microsoft to help senders track their IP health on Outlook.com and Hotmail.

Spam

Spam is any email sent to someone without their clear permission or after they have lost interest in hearing from you. It is email that feels unwanted or irrelevant to the person receiving it.

Spam Trap

Also known as: Honeypot Address, Trap Address

A spam trap is an email address used by inbox providers to spot bad or careless senders. Hitting one damages your sender reputation and makes it more likely your emails go to spam.

SPF

Sender Policy Framework is a DNS setting that lists which servers can send email for your domain so inbox providers can quickly check if a message is real or spoofed.

Spy Pixel

Also known as: Tracking Pixel, Tracking Bug

A spy pixel is a tiny invisible image in an email that tracks when someone opens it. It helps email marketers measure open rates in a simple way.

STARTTLS

Also known as: Opportunistic TLS

STARTTLS is an email protocol command that upgrades a plain text connection to an encrypted one (TLS/SSL).

Subject Line

A subject line is the short title of your email that shows up in the inbox. It gives people a quick idea of what the email is about and helps them decide if they will open it or ignore it.

Subscriber

Also known as: Recipient

A subscriber is someone who gave you clear permission to receive your emails. They chose to join your list and expect useful, relevant messages from you.

Suppression List

Also known as: Exclusion List

A suppression list is the place your email tool keeps addresses that should not receive messages. It is a permanent "do not send" list that helps you avoid emailing people who have opted out or caused issues in the past.

Template

A reusable email layout you use as a starting point for campaigns. It keeps your design consistent so you only need to update the content each time.

Test List

Also known as: Test Segment, Preview List

A test list is a small group of people who receive your email before everyone else. It is a simple way to spot problems before a full send.

Throttling

Also known as: Rate Limiting

Throttling is when inbox providers or your email platform slow or limit how many emails you can send in a set time. It acts like a speed limit so big sends do not overwhelm their systems or hurt your reputation.

Time Zone Optimization

Also known as: Time Zone Targeting, Geographic Send Time

Time zone optimization is automatic scheduling that sends each email at a normal hour in the subscriber's own time zone so messages land when they are most likely to check their inbox. It uses location or time zone data to stagger the send across regions.

Tracking

Tracking is how your email tool logs opens, clicks, and sales that come from your emails. It helps you see what people do after they receive a message so you can improve future campaigns.

Transactional Email

Also known as: Transaction Email, System Email

Transactional emails are automatic messages sent when someone does something on your site or app, like placing an order or resetting a password. They share the key details about what just happened so people are not left guessing.

Triggered Email

A triggered email is a message your system sends automatically when someone does something specific, like signing up, leaving items in a cart, or reaching a milestone. It goes to one person based on their action instead of going to your whole list at a fixed time.

Unique Clicks

The number of unique subscribers who click at least one link in your email. Each person is counted once, even if they click several times.

Unique Opens

Unique opens is the count of individual people who opened your email at least once. Each person is only counted one time, even if they open the same email many times.

Unsubscribe

Also known as: Opt Out

The action someone takes to stop getting your emails, usually by clicking a link at the bottom of a message. It is required by law and it shows respect when you stop emailing them right away.

Unsubscribe Rate

Also known as: Unsub Rate, Opt-Out Rate

The unsubscribe rate is the percent of delivered emails that lead to an unsubscribe. It shows how many people no longer want to hear from you after a send.

URL

Also known as: Link

A URL (Uniform Resource Locator) is the web address behind a link in your email. It is what subscribers click to move from your message to a page on your site.

URL Parameter

Also known as: Tracking Parameter, Query Strings

URL parameters are the text that comes after the "?" in a link. They tag where a click came from and what someone does on your site so you can see how each email link performs.

Version

A version is a specific saved state of an email or template. It lets you compare different drafts in tests and return to a known good setup if new changes do not work.

Wait Step

Also known as: Delay, Pause Step, Time Delay

A wait step is a delay in an email automation that holds the next action for a set amount of time. It keeps messages spaced out so subscribers are not hit with too much at once.

Web View

Also known as: Web Link

A web view is the browser version of your email that opens in a normal web page. It gives people a clear way to read your message if their email client breaks the layout.

Welcome Email

Also known as: Welcome Message, First Email

The first email a new subscriber gets right after joining your list. It introduces your brand and confirms what they can expect from you.

Whitelist

Also known as: Allowlist, Safe Sender List

An email whitelist is a list of trusted senders or domains that people or email systems approve so their messages go to the inbox instead of spam. It is the opposite of a blocklist.

Wireframe

A wireframe is a simple sketch of your email layout that maps out where each key element sits before you design it. It helps you plan the structure without getting caught up in colors, fonts, or final copy.

Workflow

Also known as: Automation Workflow, Email Workflow

An email workflow is an automated series of emails that sends itself based on what a person does or does not do. It uses simple rules to send the right message at the right time without manual work.

WYSIWYG

Also known as: What You See Is What You Get, Visual Editor, Live View, Design View

A WYSIWYG editor lets you build emails by dragging and typing while you see the final layout as you work. It shows a live preview so you do not need to touch HTML.