Email Glossary - Updated for 2024

Can’t keep up with the different terms used in email campaigns? We’ve got you covered! 

Let’s review the popular email terms and acronyms and their meanings, and you’ll be confidently running your campaign in no time!

A/B testing (Split testing)

In A/B testing, marketers test different versions of an email to check which generates the best results. There are different approaches to A/B or split testing; marketers can change an element, such as the signature or the Call to Action (CTA), or adjust the content by adding an image. Sometimes, A/B testing also includes adding a sender’s image or tweaking the email’s colorways.  During testing, all email versions are sent out to a set number of recipients, and the best-performing version is then sent to the remaining recipients. Need help in setting up email split testing?

Account creation email

It’s an automated email confirming the creation of an account on a platform. Account creation requires the confirmation of the user’s details, including the next steps to take to complete the account registration or verification.

API

API refers to an Application Programming Interface, which acts as a software intermediary and allows two different applications to work together. Using an API improves the user experience by automating the data transfer between two applications. An example of this is an email API.

Auto-responder or autoresponder

An auto-responder is an automated email sent in response to a specific transaction. This type of email is popularly used in customer service operations and requires immediate customer feedback and attention. For example, a customer may know how long a supervisor can take action or be informed when the service will become available. Business owners also use autoresponders to provide instant replies to users, for example, after downloading a resource or completing a survey.

Automated email

An automated email is automatically sent to subscribers based on a pre-determined trigger, for example, when the user answers a survey question or registers for a webinar. Most transactional emails are called automated emails.

Automation platform

Automation platform refers to a set of tools used to automate tasks, business processes, and even workflows. Using an automation platform makes designing and executing processes and integrating data reporting and analytics easier. Many businesses now rely on automation to streamline tasks for efficiency. For example, small business owners can now automate their transactional email campaigns, like when automating the process of receiving or confirming orders. Some of the leading automation platforms to use today include Pabbly Connect, Make, Zapier, and Integrately. You can contact our team if you want to learn more about automation platform integrations.

BCC

In email marketing, a BCC means a Blind Carbon Copy. It is a field in the email where additional recipients’ addresses can be added. You can use the BCC field if you still want to inform others about transactions or activities without directly involving them in the conversations.

Blocklist

The blocklist includes a list of IP addresses or domains that are flagged as sources of malicious activities or spam. Internet Service Providers (ISPs), Email Service Providers (ESPs), and other businesses use a blocklist to filter incoming emails and ensure their authenticity. As an individual or business owner, you mustn’t be included in the list as it can affect your sender's reputation or even the email-sending deliverability. Alternatively, a blocklist may also refer to a list of subscribers who cannot receive your emails for business or personal reasons.

Bounce rate

The bounce rate is a crucial email marketing metric for the percentage of undeliverable emails. There are two types of bounce, hard and soft, which can happen for various reasons, including a full inbox or sending to an invalid email. As a marketer, you’ll need to avoid a high bounce rate, which can affect your email deliverability.

Bulk email

Sending many emails to different subscribers simultaneously is called bulk emailing. A bulk email strategy can optimize sending in a transactional email campaign.

CAN-SPAM Act

The Controlling the Assault of Non-Solicited Pornography and Marketing Act (CAN-SPAM Act) is a law in the United States that regulates and standardizes commercial emails from different businesses and organizations. Under this law, emails are subject to compliance with the rules in generating headers and subject lines, disclosures, penalties for violations, and subscription plans. Furthermore, it gives recipients the right to be removed from email lists if a breach occurs. 

Carbon Copy (CC)

In every email message, you always have the option to utilize the Carbon Copy (CC) feature. As the name suggests, CC recipients receive an exact copy of the email message sent to the primary recipient. In this field, you can add other email recipients who do not have direct involvement with the conversation but you want them to know about the details. For example, you emailed your prospective client and added your manager’s email to the CC field. In this case, there's no need to send a separate email to your manager for updates on the conversation. 

Click-through rate (CTR)

In email marketing, the click-through rate (CTR) is the percentage of all subscribers who clicked the link in your email. To compute the CTR, divide the number of clicks by the number of sent emails multiplied by 100.

Click-to-open rate (CTOR)

The Click-to-Open Rate, or CTOR, is the percentage of subscribers who opened the email and clicked on the link. To compute CTOR, divide the number of clicks by the number of opens, multiplied by 100.

CNAME

The CNAME or Canonical Name Record is a Domain Name System (DNS) record that associates one domain name or alias to another (canonical name). This record is used when running multiple services from one IP address since it can have a DNS ancestry but points to the same IP address. Using a CNAME is helpful in larger network environments since it’s easier to track domain names.

Customer Relationship Management (CRM)

Businesses use Customer Relationship Management (CRM) to manage and assess customer data and interactions. Marketers use a CRM to record customer data, including purchase history. Installing a CRM promotes a personalized experience for team members, providing seamless communications and interoperability regarding specific transactions.

Dedicated IP address

A dedicated IP is assigned to a single sender. If you’re using a dedicated IP address, it means that you’re the only user responsible for the quality and sending reputation of the dedicated IP address. Contact us today if you want to apply for a dedicated IP address for your small business.

Deliverability

Email deliverability is the ability of an email message to reach the recipient’s inbox instead of being rejected or spammed. Several factors affect email deliverability, including, but not limited to, email authentication, sender’s reputation, email content, and sending infrastructure. Email deliverability is an essential aspect of email marketing, especially in business. If an email fails to reach the recipient’s inbox, the performance of email marketing and business is reduced.  

Delivery rate

The delivery rate is the percentage of emails that were successfully delivered to the subscribers’ mail servers, regardless of whether they end up as spam, in junk, or straight to their inboxes.

Denial-of-service (DoS)

A Denial-of-Service (Dos) is an online attack that aims to disable the server by clogging it with multiple requests until it’s unable to operate normally.

DKIM

DomainKeys Identified Mail (DKIM) is a type of email authentication that helps protect a domain from spoofing and other malicious activities. All emails have a domain, which is part of the address after the "@" symbol, and DKIM is tasked to detect if a message has been modified or if unauthorized changes have been made to the message.

DMARC

Domain-based Message Authentication, Reporting, and Conformance (DMARC) is an authentication, policy, and reporting protocol that tells the receiving servers what to do with outgoing emails from your organization that don't pass through DKIM or SPF authentication.

DNS (Domain Name System)

The Domain Name System is a directory of domain names with their corresponding IP addresses where the sites are stored.

DNS record

The DNS record of a DNS server indicates information about the domain, such as the associated IP address. This record can help authenticate emails and provide instructions on managing domain requests.

DNSSEC (Domain Name System Security Extensions)

The DNSSEC refers to a set of protocols that secure the DNS by integrating cryptographic signatures into a DNS record.

DNS server

A DNS server is a software or physical aspect of the DNS that stores information required to manage DNS queries.

DomainKeys Identified Mail (DKIM)

DomainKeys Identified Mail (DKIM) is an email authentication standard that improves security by preventing email spoofing.

Domain Message Authentication, Reporting & Conformance (DMARC)

The Domain Message Authentication, Reporting & Conformance (DMARC) is used with DKIM and SPF to help authenticate emails. DMARC allows senders to use DMARC reporting, which allows them to review the domain-sending activity and address sending issues in the process.

Drag and drop

A drag-and-drop is an email or site tool that allows users to create templates by simply dragging and dropping pre-built elements that can be customized for color, design, content, and imagery.

Drip campaign

In a drip campaign, you send a series of automated emails to a group of subscribers over a period of time. Here, emails are pre-written and set up as part of the automation process to engage and nurture a target audience. Traditionally, drip campaigns are educational and deliver value to subscribers, motivating them to perform a specific action. For example, your drip campaign may be a welcome email campaign aiming to motivate customers to shift to a paid account.

EHLO

EHLO is Extended Hello, a Simple Mail Transfer Protocol (SMTP) command that starts a session between the sending and receiving email services and assesses the server’s capabilities.

Email alias

An email alias is an alternate email address linked to the same mailbox as another address. This strategy allows individuals to use multiple addresses to receive emails from a single email account.

Email API

An email API, like Maileroo’s Email API, is an intermediary that provides the functionality of an email service to other apps using code. The API offers a set of protocols and programming instructions to directly integrate an email provider (like Maileroo) infrastructure into other apps or websites. Traditionally, an email API boasts all features of the SMTP and more, thus promoting better personalization and efficient transactional email sending.

Email automation

Email automation integrates predefined rules to make email messages more personalized based on users' specific actions. This email marketing strategy helps you quickly communicate with clients and provide customer support. You may also receive a ‘no-reply’ email. In this email automation, you cannot send reply messages, as they will not be sent to the sender anyway. 

Email blast

Businesses can send many subscribers a blast or mass email at once to promote a product or service or spread a specific message.

Email client

An email client is a mobile, desktop, or web software application used to access and manage users’ emails, with additional features that allow them to send and receive messages, manage contacts, or even filter emails. Some of the popular email clients today are Gmail, Microsoft Outlook, and Apple Mail.

Email encryption

This email authentication process converts plain texts into codes to prevent unauthorized individuals from reading the message. Web-based email services use encryption technologies like Secure/Multipurpose Internet Mail Extensions (S/MIME) and Transport Layer Security (TLS). Another way to encrypt emails is through end-to-end encryption using public keys. Intended recipients are the ones allowed to view and read the message. 

Email hosting

Email hosting is a paid service that provides email servers and accounts for all types of users. With email hosting, you can use your domain name to customize your email addresses, which you can’t do with commercial email clients like Gmail and Outlook.

Email list

An email list is a list of email addresses an individual uses to send messages. If you’re running a transactional email campaign, emails are instantly added to the list if a customer creates an account, buys a product, or completes an action. In email marketing, subscribers become part of the list if they sign up to receive news or newsletters.

Email marketing

Email marketing is sending promotional offers to a targeted audience using emails. There are different types of email marketing campaigns, with newsletters and emails about product teasers and launches being the most popular. Unlike transactional email, email marketing lets you send promotional messages. As such, most businesses run separate campaigns for their transactional and email marketing initiatives.

Email personalization

Email personalization is customizing the content or subject lines using the subscribers’ information or account activities. There are different approaches to personalization, like inserting the customer’s name and address or tweaking the messaging by touching on their recent purchases. Also, email personalization can help in designing a targeted campaign based on a specific transaction.

Email relay

Email relay transfers an email from one server to the next until it reaches the subscriber’s inbox.

Email server

An email server is a software program that allows storage and delivery of email messages to intended recipients. Email servers may vary for incoming and outgoing messages. The Post Office Protocol version 3, or POP3, is the most common incoming server. Meanwhile, outgoing mail servers are known as Simple Mail Transfer Protocol (SMTP). 

Email signature

An email signature is an image or a block of text added at the end of the message. Signatures can include contact details, social media links, or even the sender’s details.

Email template

Senders can use a pre-designed format or layout for emails, which we call an email template. By using an email template, you can easily populate it with specific information or brand elements.

Email tracking

In email tracking, a marketer can easily track the activities on the emails like opens, number of clicks, unsubscribe, or even rejections.

Email validation

It is the process of verifying the validity of an email or list of email addresses. Soft bounce or hard bounce may happen on undelivered mail. Thus, email validation is important to identify potential frauds or low-quality email messages. 

Endpoint

The endpoint is a web address or a specific URL that serves as the touchpoint for the API where two apps communicate with each other. It’s often used to retrieve data from a web app or server. The API provider often defines the endpoints for sending emails or fetching email activities.

Hard bounce

A hard bounce refers to an email delivery failure due to several reasons and errors. This happens if the recipient’s email address does not exist or if the email service has permanently blocked email delivery. 

HTML email

A Hypertext Markup Language (HTML) email uses message contents more than just plain text. It may contain images, stylized fonts, multimedia, and even hyperlinks. 

HTTP method

The HTTP method refers to a set of standardized commands to request actions so that a user can perform with a REST API. Some examples of commands include PUT to replace data, DELETE to remove data, or GET to collect data.

 Identifier alignment

An identifier alignment is a DMARC step that compares the sending domain with the “From” sender’s address.

IMAP

IMAP stands for Internet Mail Access Protocol, which email clients use to fetch emails from the servers.

IMAP client

An IMAP client is a web-based, mobile, or desktop program that allows users to manage their emails from the mail server using the IMAP protocol. Today's leading IMAP clients are Apple Mail, Gmail, Thunderbird, Mozilla, and Microsoft Outlook.

IMAP server

The IMAP server handles the retrieval of emails for client email programs through IMAP. This server type allows users to see or access an email across different devices or clients, even after the original recipient has already seen or downloaded the message.

IMAP4rev1

The IMAP4rev1 is the latest version of the IMAP protocol, boasting UTF-8 and metadata support.

Inbound routing

Inbound processing allows Inbound emails to be routed to an email service provider (ESP). For instance, a transactional API processes inbound messages and delivers results to a web app like Webhook. This also allows users to add comments and respond to emails. 

 Internet Service Provider (ISP)

An Internet Service Provider or ISP is a general term for an entity that offers Internet-related services. Outlook.com, GoDaddy, and Verizon are examples of ISPs that deliver web-based services to individuals and businesses.

IP address

Internet Protocol (IP) addresses consist of unique strings of characters assigned to every device. They allow devices to connect to the Internet and communicate with other devices over a network.  

IP allowlist

This lists all IP addresses with authorized access to a network service and deployed endpoints. All IPs not included in the list will be rejected. 

JSON

JSON or JavaScript Object Notation that facilitates the exchange of data between the client and a web server.

List hygiene

List hygiene involves regularly cleaning and updating the email list to ensure it only contains engaged and active subscribers. An effective list of hygiene includes removing inactive or invalid email addresses, as these can impact email deliverability and sending reputation.

List segmentation

In list segmentation, subscribers are grouped into smaller groups based on specific criteria, such as behavior, interest, or demographics. Business owners can easily configure their email content using list segmentation based on the recipient’s interests and needs.

Mail client

A mail client is a web-based service or software program that allows you to send, receive, or manage emails. Some top examples of mail clients are Mozilla, Microsoft Outlook, Gmail, and Apple Mail.

Mail server

A mail server is a program or an application hosted physically or virtually that manages the delivery and storage of emails from multiple email domains. Servers communicate with each other to allow the sending and routing of emails to the intended subscribers.

MDA (Mail Delivery Agent)

The Mail Delivery Agent (MDA) is software that receives email from the server and directs it to a targeted inbox. It also acts as an intermediary between the mailbox and mail server and works with the Mail Transfer Agent (MTA) to transfer emails between servers.

MSA (Mail Submission Agent)

The Mail Submission Agent (MSA), also called the Message Submission Agent, receives messages from the Mail User Agent (MUA) and works with the Mail Transfer Agent (MTA) to ensure emails arrive at the right inboxes.

Mail Transfer Agent (MTA)

The Mail Transfer Agent (MTA) is an email server software responsible for receiving and relaying email messages. Email messages may come from another MTA or a Mail User Agent (MUA) sent via SMTP. 

Mail User Agent (MUA)

Mail User Agent (MUA) is a software application that allows users to access a mail server to create and deliver messages. Some popular MUAs are Apple Mail, Gmail, and Microsoft Outlook.

MX (Mail Exchanger) records

The Mail Exchanger (MX) records are DNS records that indicate which server is tasked to handle an email for a particular domain. Email systems rely on the MX to route emails to the right server.

Notification email

A notification email is a specific email sent to subscribers about important updates to their accounts or purchases. These are often generated and sent automatically, triggered by a specific action. Some common examples of notification emails include account status updates, support service notifications, and shipping updates.

Open rate

Open rate is a crucial email marketing metric that measures the percentage of subscribers who open messages. You can calculate the open rate by dividing the number of opens by the total number of emails multiplied by 100. Marketers use the open rate metric to measure engagement and to see the effectiveness of the email subject line.

Opt-in

To opt-in means to give permission to receive emails from a specific sender. If you’re running a transactional email campaign, opt-in consent is not required since it’s already implied that they’re open to receiving emails upon registration. But if you’re running an email marketing campaign, the subscribers’ consent is required before sending promotional materials like newsletters.

Order confirmation

An order confirmation is a transactional email sent to a recipient to confirm an order. A typical order confirmation email often contains the recipient’s order number, quantity, amount, and estimated delivery time.

Password reset

Subscribers who lost their passwords can request a Password Reset. To reset a password, the subscriber simply clicks the link to the password reset and types in a valid email address. The subscriber will receive instructions on changing the password on this address. However, Google and other online email services send verification codes to registered mobile numbers before the system sends instructions on changing the password. This extra authentication ensures that the users’ accounts remain safe.

Person-in-the-middle (PITM)

It’s a type of attack in which bad actors intercept email messages in transit to recipients in an effort to gain information or change their content.

Phishing

Phishing is a common online attack in which hackers try to steal personal information by sending users emails or messages that impersonate legitimate websites. A phishing email often asks the unsuspecting user to click on a link, provide details, log in to an account, or download a document or attachment with malware or a virus.

POP

Post Office Protocol (POP) fetches emails from servers and delivers them to the right inboxes. Under this protocol, the recipient is responsible for deleting these emails.

POP client

A POP client is a web-based, mobile, or desktop program that allows users to access and manage emails from the server using the POP protocol. Examples of POP clients are Opera, Apple Mail, Thunderbird, and Microsoft Outlook.

POP retrieval

POP retrieval refers to fetching emails from the POP server on a client using the POP protocol. Emails can be deleted once they have been downloaded from the POP server. In short, when you access your messages on the POP server using different apps or devices, these may display different emails. Some POP email clients can be configured to leave a copy of the message on the server.

POP server

This specific server is tasked to retrieve the messages for the client email programs using the POP protocol. Once the email client downloads the messages, these are often deleted, meaning different emails may be displayed across apps or devices.

POP3

POP3 is the most recent version of the Post Office Protocol (POP), which is used to fetch emails from the mail server.

Preheader

The pre-header is in the inbox next to the email’s subject line. This section allows a sender to expand the subject line and provide more information about the email’s content.

Reporting URI for aggregate data (RUA)

This is an example of a DMARC tag that indicates the email address used to collect the aggregate of email activities.

Reporting URI for failure data (RUF)

A specific DMARC tag indicates the email address to collect the forensic reports of messages that failed the authentication process.

REST

REST stands for Representational State Transfer, a software architectural style that uses website standards to create interactive web apps.

Rich Text

The Rich Text is a format used to generate Rich Text content. When used for emails, Rich Text lets users create plain text-type emails, with the ability to use the formatting capabilities of HTML, such as underlined or bold texts, usRich Text is a format used to generate rich text content. When used for emails, Rich Text lets users create plain text-type emails with the ability to use HTML's formatting capabilities, such as underlined or bold texts, links, and different fonts and images.

SDK

SDK stands for a Software Development Kit and refers to tools offered by the platform’s developer to streamline the integration and development of apps. The SDK lets the marketer use the platform’s framework or the platform.

Secure Sockets Layer (SSL)

The Secure Sockets Layer (SSL) is an encryption protocol that is used for data privacy and network authentication. Websites use SSL to encrypt data transfer between the website browser and other applications. The Transport Layer Security (TLS) is the most recent SSL update, released in 1999.

Sender ID

Sender ID is Microsoft Exchange’s historical authentication method that lists the IP addresses of email servers that are allowed to send messages from a domain.

Sender Policy Framework (SPF)

The Sender Policy Framework (SPF) is an email authentication standard that displays the sending IP of mail servers allowed to send emails from your domain. This is implemented as a DNS TXT record and is an important protocol for sending emails.

Sender reputation

A sender's reputation measures the trustworthiness or credibility of an email sender and can impact how emails are delivered to inboxes. Several factors can influence the sender’s reputation, including email content and engagement, sending behavior, and blocklist appearances.

Shipping confirmation

Shipping confirmation is a popular transactional email sent to customers after the purchased item has been shipped. A typical confirmation often includes the customer's name, the shipping address, the type of item, its tracking number, and an estimated date of arrival.

SMTP authentication

SMTP authentication is the process of identifying the identity of the email’s sender, often through the use of a username and password and popular authentication methods such as LOGIN, PLAIN, or CRAM-MD5. Marketers use SMTP authentication to stop unauthorized access to and use of email accounts, which can reduce abuses such as spamming and other forms of online attacks.

SMTP error codes

Email servers use SMPTP error codes to indicate the status of deliveries. These error codes are three-digit numbers that correspond to a specific delivery error.

SMTP port

The SMTP port is a logical address that locates a specific network address.  If a computer program communicates with a network service, it connects to a specific SMTP port.

Simple Mail Transport Protocol (SMTP)

SMTP is an Internet-standard communication protocol used to send and receive emails between mail servers and other message transfer agents (MTAs). 

SMTP relay

Simple Mail Transfer Protocol (SMTP) relay is an email delivery service between servers using the SMTP protocol. You can choose between an open relay and a closed relay SMTP service for email services. In an open relay service, emails are sent from internal and external sources. Meanwhile, closed relays allow you to send internal server emails only. 

 SMTP server

Simple Mail Transfer Protocol (SMTP) servers are needed to send email messages to any recipient. These are trusted outgoing third-party servers that relay email over SMTP.  

SPF

Sender Policy Framework (SPF) is an email authentication standard that protects users from spoofing, spam, and phishing. Marketers and business owners add an SPF record to the Domain Name System (DNS) to provide a public list of authorized email senders to a specific domain.

Soft bounce

While a hard bounce is permanent, a soft bounce is a temporary email delivery failure. This happens when the recipient's inbox is full, so the email message is returned to the sender. Soft bounce may also be caused by temporary server maintenance, inappropriate message size, and detection of potential spam. 

Spam

Spam is unwanted, unsolicited, or irrelevant email messages. Spam emails are often sent in bulk to customers who have not consented to receive these messages. Traditionally, these messages contain overly promotional content or in extreme cases, contain fake information or may be used for phishing attempts.

Spamming

Spamming is a questionable tactic of sending unsolicited messages to many users. Email spam or junk emails may contain links used for phishing and are often used to deceive users into sharing their personal or banking information.

Spam filter

The spam filter is a tool administrators and email service providers use to identify and block suspected spam or suspicious emails.

Spoofing

Spammers use this method to trick email recipients into opening emails as part of phishing and fraudulent attacks. Spoofing is done by faking email addresses, similar to legitimate email addresses from a person or brand, or providing forged email headers. Once a recipient opens the message, it may result in accessing and sharing sensitive personal information. 

STARTTLS

STARTTLS is a type of command received by an email server from an email client. This command informs or directs the email server to upgrade to a more secure connection.

Subject line

This is one of the most important fields in an email message. It contains texts that preview the email content, which may influence the recipient’s actions to open the message and responses. 

Suppressions

Suppressions refer to a list of addresses that marketers have removed from the recipients’ list, which will no longer receive transactional or marketing emails. Often, suppression lists feature addresses that have unsubscribed, hard bounced, made spam complaints, or became invalid for one or two reasons.

Transactional email

Transactional emails are automated messages that contain information linked to the customer’s action on the app or website. They are triggered by a specific transaction, such as a purchase, signing up for an account, or password reset.

Transactional SMS

Transactional SMS are automated text messages that contain information linked to a customer’s action on the app or website. Examples of transactional SMS are appointment reminders, shipping notifications, and 2FA notices.

Transport Layer Security (TLS)

Transport Layer Security (TLS) is a cryptographic protocol used to secure data transferred online.

Triggers

Triggers are specific actions or events that cause an automated email or SMS to be sent or another event to occur in the workflow.

Two-factor authentication (2FA)

Two-factor authentication requires two steps to access a system or an account. For example, if you’re using Gmail, you’ll be asked for a code via text message in addition to the standard username and password.

Unsubscribe

To unsubscribe means to opt out of receiving specific types of emails from a sender.

Webhook

Webhooks allow real-time notifications about events or actions. These may feature a message or payload and be sent to a unique URL, often the app’s address or phone number. Webhooks are often used to connect systems or apps, allowing real-time data sharing.

Webmail

Webmail is a web-based email client that lets you access and use emails using a web browser.

Whitelisting

Whitelisting refers to the practice of adding new email addresses or domains to the safe senders list, ensuring that they will receive future emails or communications.

Workflow

Workflow refers to a series of tasks or actions triggered by a specific event. For example, a workflow is triggered when a user creates an account or a customer finally purchases.