Email glossary

A compilation of all the concepts you need to know to become an emailing expert, explained in the simplest way possible.


A/B testing is the act of sending two version of an email which contain the same information but are presented in different ways. This kind of testing is carried out to see which of the emails performs better and has greater open rates. Whichever is the more successful will be the email that will be sent out to a wider audience.

Acceptance rates are metrics used to measure how much emails from a campaign were not bounced back from the receiving email servers. It is different to deliverability in the sense the acceptance rates include anything that wasn’t bounced, including mail that doesn’t arrive in the intended mailbox.

An alias email address is an alternative email address to your personal one which still directs mail to the same original inbox. Alias email addresses are especially useful for businesses who can have a business address which they share with business contacts, which is all kept in the same handy place as their personal emails.

An alternate email address is essentially another email account which you have alongside your primary address. You might set up an alternate email address for your business for example, or to manage your household email correspondence.

When your email inbox gets too full, you can choose to archive your emails. This means storing them in a special folder so that they don’t show up in your email inbox. Archive email is what we call these emails that are stored in your archive.

An email attachment is a file that can be sent with an email, which the recipient can view or download if they choose. The files can be documents, audio files, videos and more.

An autoresponder email is a tool that you can use to automatically send an email to an individual contact or multiple contact.


Base64 is a collection of encoding schemes that are binary to text, representing binary data in an ASCII string format. They can be used to transfer text and sometimes images into a string which can be read, saved or transferred.

BCC stands for blind carbon copy – so what is a blind copy email? Like a CC email, a blind copy email is an email you send to someone, while also copying in another recipient. The difference is that the main recipient isn’t aware of the second recipient.

BIMI is an acronym that stands for Brand Indicators for Message Identification. This new kind of email specification, backed by Google, Mailchimp and Sendgrid, offers the ability to attach your brand and logo to the emails you send. Similar to DMARC and DKIM, it is an authentication method which includes the brand and logo of a company within an email to establish the email as genuine.

Email blacklists or blocklists are lists that are updated in real-time containing IP addresses and domains which are deemed to be fraudulent or spammy. Emails sent from these addresses and domains will be automatically sent to the spam file, and often the addresses and domains themselves will be blocked from sending on email servers.

When you send out large numbers of emails all at the same time, most will likely arrive at their destination. However, some may “bounce” which means they won’t arrive in any inbox. The bounce rate is the number of these emails that bounce compared to those that arrive at their intended address.

A bounce in email means that the email sent didn’t reach the recipient.

Bulk email is large numbers of emails all sent at the same time. Bulk email software allows marketing teams to reach a very wide audience of recipients with just one click – it often is used as part of a campaign to spread the word quickly and effectively via email. Most of the time, it’s best to avoid sending emails in bulk to protect your account and prevent spam. The best practice to avoid getting blocked when sending emails in bulk is to split your email campaigns in smaller batches and send them across several days.

A burner email is an email address that you can set up if you don’t want to share your personal details with a business that requires an email address to access.


A call to action or a CTA is a piece of text or a button that asks or suggests that the reader should take an action. That action can be calling a number, sending an email or clicking through a link to a website.

CAN-SPAM, also known as the Controlling the Assault of Non-solicited Pornography and Marketing act, is a piece of legislation passed by the United States of America in 2003. It sets the standard for how marketers can send marketing materials that haven’t been requested by the recipient, letting them know what the can, and can’t, do.

Canned emails are pre-written emails that are automatically sent to emailed enquiries to provide answers to frequently asked questions. Some email clients and email service providers, such as Gmail, allow you to write these emails as automatically templated responses.

CASL stands for Canada’s anti-spam legislation, and is a law that regulates how much unsolicited email marketing a business can send in Canada. It is famous for being one of the toughest anti-spam laws in the world, and requires anyone that sends commercial electronic messages to get permission or consent from the recipient before they send anything.

A catchall email is an email address which will collect any emails that are sent to an incorrect email account on a domain. If an email is sent to an address that doesn’t exist on a domain, the catchall email account will collect that email so that the domain owner can see them.

CC stands for carbon copy – so what is cc on email? CC on an email is where you can add multiple secondary recipients to the same email. These CC recipients aren’t the same as the main recipients, but they do get to see the email thread too.

Click rate is a metric used by marketers to compute how many people clicked a link or an image on the emails they sent. This rate gives an overview of how good the email’s content is for encouraging the reader to take another action, showing the marketer what needs to be improved for the next email campaign.

Click through rates are what marketers use to see how many people clicked on a link or an image on the emails they sent. These rates give an idea for how good the email’s content is for encouraging the reader to take another action, showing the marketer what needs to be improved for the next email campaign.

Cold emails are emails that are sent to recipients who haven’t asked to be contacted – or have never been in contact with the sender. They are often used by marketers to start a conversation or to inform the reader of a product or service. Cold emails are unsolicited – but is cold email illegal? The answer is no, sending cold emails is not illegal – but it can be annoying for the recipient. You may want to check the law applicable in your country and the ones of your recipients before sending cold emails to ensure you”re compliant with the legislation.

An email complaint is when a recipient flags an email for spam. The complaint rate measures how many of the recipients flagged the email for potential spam and abuse. A high number of complaints can put the sender’s reputation at risk.

To compose an email is another term for writing an email. For many email providers, you”ll see a button that says “compose email” which, when clicked on, will let you start writing an email to be sent to a recipient.

When you make a purchase online or sign up to something, like a newsletter for example, you”ll receive a confirmation email from the business or organization. These emails are there to confirm that your order has been placed or the action you took on their website has been successful.

Everyone has a contact list in its smartphone. In emailing, it’s very similar. A contact list is a collection of email addresses, sometimes with more information about each recipient, such as:

Conversion rate is a marketing and business metric which measures how many recipients of marketing emails take an action based on those emails. An email with a high conversion rate is one that inspires a lot of people to click on a link or buy a product for example

CRM stands for Customer Relationship Management and it is a tactic used by businesses to improve their relationship with their customers, using things like data and research to create more targeted and relevant marketing materials.

A custom domain is a domain that has been given a customized name, as opposed to one that uses another brand’s name. They are unique labels, attached to IP addresses of websites, and can be used to establish that an email has come from a familiar business.


A dedicated IP address is one that can only be used by and for your domain. These addresses aren’t shared by other devices and domains – they are exclusively for you. Sometimes, they can cost a little bit extra for the added security and privacy they bring.

Email deliverability is the word that describes how likely it is that your emails will be read. It measures how many of your emails will land in your recipient’s inbox folder instead of spam. What does deliver mean? Delivering is another word for getting an email from one account to another.

A disposable email addres is an email address that you can create when you don’t want to share your personal email address.

DKIM is an acronym for DomainKeys Identified Mail. It is an authentication protocol that allows anyone receiving emails to check that those emails were actually sent by the genuine sender. DKIM does this by including a digital signature in the form of a header with every email.

DMARC stands for domain-based message authentication, reporting and conformance. It is an authentication protocol that authenticates emails and protects your email domain from being used by cybercriminals for phishing and scamming purposes.

Double opt-in is a method for opting in or subscribing to an email newsletter or marketing communications. Where single opt-in mechanisms would let you sign-up with just a single action, such as clicking a button on a website, double opt-in methods combine two mechanisms – such as signing up by a button on a website and then confirming that opt-in with an email requiring an action.

An email drip campaign is a number of automated marketing emails that are sent out at set times and at a set rate - for example, a welcome email sequence sent to new customers. So what is drip email? Drip emails are emails that are sent one at a time as part of a planned schedule, as “drips” of emails, one after the other.

Dynamic email is email content or parts of an email that can be automatically personalized to the recipient. It can include things like names, businesses, order numbers, dates of births, and is included by using variables in mailing lists.


An email address is an address for an email box where messages can be delivered and sent. All businesses and most individuals have an email address for professional and personal reasons – they are made up of a local part, which is normally a name, and the domain. Are email addresses case sensitive? No – while passwords are case sensitive, email addresses are not.

Email authentication is the process of ensuring the sender of an email and the email itself are authentic, genuine and not cybercriminals seeking to fool recipients into scams or fraudulent activity. There are many forms of email authentication, all designed to certify the sender as a real and trustworthy figure.

Email automation is where a series of emails are sent automatically as part of a schedule. The automation part means that the sender doesn’t need to manually click the send button every time – the software will send the email on his or her behalf. In certain cases, automation can be triggered by specific events, such as when one of your recipients reads, opens or clicks your email.

An email blast is a scheduled marketing method that sees email marketing professionals send a “blast” of emails, all at the same time and all with one click of a button. The emails in the blast are sent to a wide range of recipients, held on the same distribution list and containing similar marketing content.

Email campaigns are a series of emails, sent by a business or organization, to promote either a product or a set of services. These emails will be used to encourage the reader to take an action, whether it’s visiting a website for more information or even directly making a purchase. Marketers will use email campaign software to create the campaign and to automatically send emails at set points.

Email clients are platforms and pieces of software which enable you to send and receive emails. Some contain other tools and features to help schedule and manage email, such as calendars, address boxes and more.

Engagement is a series of metrics used by email marketers to measure how people are interacting or engaging with the marketing emails they send out. Commonly used metrics include things like number of replies, open rates, conversion rates and click rates, and they can be used to see what works in emails, and what doesn’t.

Email filtering is an automatic tool which many email clients have which separates different incoming emails into a series of folders, based on what the content of those emails are. Email filtering is also used to automatically send potential spam mail to the junk folder.

Email finders are software that allows a user to access lists of emails that the finder has sourced from the internet. These finders will scrape or scam HTML webpages to search for email addresses which they will then provide to a user for a fee. The user can then use the addresses for the email marketing campaigns.

Email harvesting is where you collect a large number of email addresses to be used for marketing purposes. Often email harvesting will be carried using an email parser, which will scan emails and texts to automatically pick up any email addresses which will be added to a list. These lists can be used to target recipients with cold email communications.

An email header is a piece of code attached to every email which shows the sender, the recipient, the date when the email was sent and the subject line of the email. That also track an email’s route which helps with things like security and authentication - keeping the recipient and sender safe from interception.

Email lists are lists of email addresses which are collected through website forms or newsletter subscription forms. Email lists can be used by the owner to send email campaigns.

Email marketing is the term used for kinds of marketing that are promoted through emails. Email marketing software and email marketing content are used to promote services and products, while features like automation and campaigns can ensure that content gets to as big an audience as possible.

Email migration is where emails are moved from one email client to another email client. For example, if you had Microsoft Outlook on your computer, but you wanted to move to Mozilla Thunderbird, email migration would be the action of moving all of your emails to the new Thunderbird client from Outlook.

Email newsletters are regular scheduled emails that contain updates about a company, an organization or an individual. Newsletters will inform the reader on recent news and events that have happened that may be of interest, and sometimes they will be used to promote new products and services.

Email parsers are pieces of software which are used to automatically read emails and pull out key information for the recipient – such as payments, addresses and other examples of relevant information.

Email phishing is an illegal practice where a sender sends an email pretending to be someone the recipient knows in order to get them to open the message. On opening the email or attachments, the recipient becomes open to having their data stolen or to have their computer infected by a virus. A common example of email phishing is a fake bank notification by email where you are asked to fill in your credit card details.

An email prefix is the part of an email address that comes before the @ sign. These are used as identifiers to show who is sending the email – as an example, the hello in is an email prefix.

Email scraping or email scrapers are programs which uses automation to scan messages and texts and to draw out key information or data that the user requires. They can be used to extract email addresses for example, or to pull out phone numbers, prices and regular mail addresses.

An email sequence is a series of emails between two or more recipients that make up an email-conversation. Email sequences can contain any number of emails, but they are always about the same topic over a number of different replies and responses.

When you send an email, you send it through an email server. These servers are computer systems that manage the sending and receiving of emails for users, instantly connecting with other servers to deliver mail between email addresses. They are essential for emails to reach their final destinations.

An ESP, or an email service provider, is a business which provides other businesses with email services. The most well-known ESPs are Gmail, Outlook, AOL, Yahoo or GMX. Often, these services can be used in pair with an email marketing platform, which is a type of software from which you can manage your email campaigns as an email marketer.

An email signature is a snippet of text which you can write which will be attached to every email you send from your email account. People use email signatures to save themselves from having to write their name and details at the end of every email they write.

Email templates are pre-set emails which can be populated by specific content. They act as starting points for your emails, saving you from having to write new emails all the time and helping you to follow your brand guidelines to maintain consistency for your business. Email templates are features of most email service providers and platforms.

An email thread is a series of emails that follow a conversation. These email threads will contain initial messages and replies which usually run through the same topic. In an email thread, emails are stacked from the oldest to the newest. It’s possible to turn off email threading in Gmail if you would rather view your email conversations separately.

Email validation is a process which ensures an email address is deliverable. An email validation tool will run through lists, verifying each email address to let the sender know if the address is valid or incorrect.

Email verification is similar to email validation in that it is a process of checking an email address to see if it is valid or if it is incorrect. This is important for email marketers to ensure their emails are being read and delivered.

Email warm up is a method of getting a good reputation for your email address to ensure your emails make it through spam filters and your address doesn’t get added to an email blacklist. Many email providers will treat a brand new email address as potentially suspicious until it gets a reputation – to build that reputation, it’s important to only send a small amount of email at a time. Once you have done this for a while, you can start to slowly send more and more as your email gets warmed up.

Emails, or electronic mail, are messages which can be sent by the internet to different devices – so what’s the difference between email and instant messaging? Emails are messages which are sent to devices to be viewed – instant messaging is where two people, logged onto the same server, exchange messages instantly.

An encrypted email is an email that has been secured by the sender to ensure that no one other than the recipient can read what the email says. The text in the email will be electronically scrambled as soon as it is sent, turned from plain words into cipher text. Once it arrives at its intended destination the reader will be able to read it. This is the most secure way of sending emails.

Email remarketing is a marketing tactic where you send specific emails to specific people, tailored to their interests, based on their behavior. These remarketing emails are more targeted, which makes them more relevant to the reader and more likely to be opened.


Follow up emails are emails that are sent to a recipient who has already been contacted in the past. They act as messages to remind the recipient of earlier emails that have been sent and to encourage a reply or an action taken on their behalf. In terms of the auto follow-up meaning, auto follow-ups are follow-up emails that are sent automatically, on a set time after the first email.

If you receive an email which you would like someone else to see, you can “forward” the email to another recipient. When forwarding an email, you can also add a new message or attachment of your own, ahead of the forwarded email to give more information.


GDRP stands for General Data Protection Regulation. It is a law within the European Union and selected other countries that ensures that businesses are careful when managing the data they collect about their customers. The regulation requires these businesses to store data securely and to not use the data in ways that could potentially harm the customer.

Gmail is an email service which is provided by Google. Users can use this service to receive and send emails quickly and easily through Google’s servers.

GMX Mail is an email service, provided for free by GMX (Global Mail eXchange) an email platform located in Germany. The service provides an email account, along with other handy tools like organizers, address books and more for a complete suite of productivity software. It also uses two-factor authentications for all users for added security.


When an email can’t be delivered to an address, it will “hard bounce” which means that it can’t be delivered at all. Unlike a soft bounce, which means an email address can’t be reached temporarily, a hard bounce means that an email address can’t be accessed at all, permanently.

Holiday marketing is the act of creating marketing materials on a number of channels, all focused at specific times of the year around specific holidays or events. These can include things like marketing across the Christmas period, or around the end of Ramadan for example. Often they will feature services or products that are relevant to that celebration.

A honey pot is a cybersecurity method which operates as a trap to lure in cybercriminals. The attackers attack a deliberately vulnerable computer or device and the breach gives you the opportunity to learn more about their methods and the vulnerabilities in your systems.

An email host name is the name of the host which you use to send emails. Hosts are services like Microsoft Outlook or Gmail, servers through which your emails will be sent and received. The host name is the name of those servers – these come after the @ sign in your email address.

HTML emails are a kind of email that have images, colours and graphics along with text. These are the opposite type of email to plain text emails which will only ever use text. HTML emails are commonly used by marketers and businesses because the images and formatting will make them stand out to the reader and encourage them to read the email and take action.


IMAP stands for Internet Message Access Protocol. It is a way for you to access email, similar to POP. IMAP is used for when you need to access email from a range of devices such as phones, tablets and laptops – you aren’t downloading the email when you use IMAP; rather you”re reading it straight from the email service.

Inbound marketing is a kind of marketing that seeks to attract customers by presenting them with attractive, valuable and engaging content that is relevant to them. On the opposite, outbound marketing is the action to reach out to your targeted audience using direct sales for example.

IP warming is the process of establishing a new IP address as a genuine one. It involves sending small volumes of emails at one go, and slowly increasing the number of emails so that email inbox providers approve your IP addresses. These providers are suspicious of new IP addresses or that haven’t been active for a while – IP warming helps establish a reputation for the address.

IP addresses which are brand new, or that have been inactive for a period of time, can often be considered potentially fraudulent or spam by email servers. To ensure that emails from an IP address make it to the recipient’s inbox, the address needs to be warmed up – this process involves sending only a small number of emails first, before building up the volume to establish a reputation for the IP address.


A landing page is a web page that is designed for a marketing campaign. Marketers will include links and call to actions in their email campaign, which will take potential customers to landing pages designed to drive conversion or provide more information.

Lead nurturing is the marketing strategy of creating relationships between the business and customers, supporting them throughout their journey in buying products and services. Lead nurturing includes sending messaging and marketing materials to “nurture” potential customers until they convert.

List segmentation is the action of splitting your contact lists into smaller, more targeted groups, such as age, gender or other categorizes. Doing so allows you to send certain, more relevant content to these groups rather than just sending the same email to everyone and getting fewer results.


Mail merge is the action of sending a large number of emails, with personalization or not. Mail merge solution (sometimes shorted as “mail merge”) is a software that automates the process by taking a mailing list and an email template to merge them together, sending an individual email to each recipient.

Mass email means collecting a large number of emails together and sending them all at the same time. Email marketing professionals use mass email to reach large numbers across a wide audience, all in one go.

Multivariate testing in email marketing is the practice of sending multiple variations of an email at the same time, to see which of these variations is the most successful and the most read. Unlike A/B testing, which only sends two email variations, multivariate sends more to get a broader idea of what works and what doesn’t.

An MX record stands for “mail exchange” record. It is a kind of DNS record that tells mail servers to accept your outgoing emails and directs incoming mail to your domain. Faulty MX records can mean that you won’t receive emails so they play an important role in your email operations.


It the good old days of the emailing communication, businesses started to send emails from noreply addresses. When you received an email from a no-reply address, it means that messages sent to it won’t be read.


An on-boarding email is an automatic email which a company will send after you have subscribed to their service or their communications. It will often contain educational information about the subscription, the service or the product to help “on-board” the recipient.

Open rate is a term used by marketers that refers to how many marketing emails are opened by recipients. Open rates are useful to understand how well emails are performing and how much people want to read what the emails say.

Opt out in email refers to the unsubscribe button in an email. When you sign up to an email newsletter or regular email updates, the opt out option is what you click to tell the sender you no longer want to receive this email correspondence.

The outbox of an email account is where emails wait before they get sent to their final destination. Once you write an email, that email is then placed in the outbox where they will establish a connection to the server to be sent on.


Personalized email is marketing email which has been tailored to its recipient. There are many ways to personalize an email – from as simple as including the recipient’s name at the start of the email to as complex as including targeting products that the recipient specifically may be interested in. Personalized emails stand a much higher chance of being open and read, rather than more generic, broad email.

Plain text email is email that only uses text as its content. There aren’t any pictures, colours or graphics involved, it is only written text. Most emails sent between individuals will be in plain text whereas business will often use HTML text instead, which is email that uses HTML coding to include formatting, images and more.

Preview text is the short bit of text that you will see under each email subject line in your inbox. The text lets you preview the email’s content, so that you can get a general idea of what the email will say before you open it.

A primary email is the main email address which you choose to receive mail to. This will be the email where you will want the most relevant email to you as an individual to go to. Primary emails are different to alternative email addresses and alias email addresses.

A proxy email address is an email address which can be used to direct emails to another primary email address. You can have multiple proxy email addresses which all connect a single primary address which collects all mail in one handy place.


Queued emails are emails that are waiting to be sent by the server. What does it mean when an email is queued? Generally, queued emails can’t be sent immediately – whether because of a connectivity issue or because of an issue with the email provider. Once the problem is resolved, the queued emails can be sent. Sometimes, email platforms will queue email to avoid sending them all at once, ensuring a higher email deliverability.


Recipient simply means the person to whom you”re sending an email to. If you were sending an email to a family member, that family member would be the recipient of that email.

Reply all is a feature in email platforms which allows you to reply to all of the recipients of an email at the same time.

In general, when you send an email to someone, you expect that person to reply directly to you. But in many use cases, especially for businesses, it might be useful to send emails from one address and invites the recipient to reply to another.


A shared IP address is one that is shared across multiple domains belonging to different parties. Often, smaller businesses will use shared IP address in accordance with their smaller budgets – however, the behavior of one site or domain can negatively affect the reputation of everyone who shares the same IP address.

Single opt-in is a method of subscribing to a service or communications. Single opt-in methods like filling a form in on a website, or clicking a subscribe button, are “single” because you only have to do one of them to subscribe. The opposite method is called double opt-in, and it means you have to do two rounds of opt-ins to subscribe.

Unlike bounced emails which can’t be delivered, emails that soft bounce are emails that only can’t be delivered for a short time. This is normally because of a problem with the recipient’s inbox – once the problem is fixed, the soft bounce email can be received.

Spam filters are automatic filters which inboxes use to separate spam or junk email from email that the reader would want to read. These filters use automation to scan emails for signs that they may be fraudulent or unsolicited, and once an email is identified as such, it is sent to the spam folder.

Spam email is unwanted email sent by both legitimate and fraudulent senders to encourage readers to take an action, such as buying something or sharing personal details. Also known as junk mail, spam emails are often sent out in large numbers to a large recipient list to try and get as much of a response as possible.

SPF is short for the Sender Policy Framework. It is a protocol which is used by domain administrators to clarify the email servers which they send their emails from – this is to prove their authenticity and to prevent emails from being forged.

SSL stands for Secured Socket Layer – which is a way of encrypting the connection between an email client and an email service. It’s a method of ensuring your emails cannot be seen by others and confirms that your emails are coming from your address through authentication layering.

The subject line of an email is a short piece of text that gives a summary of what the email will be about. When writing an email, you have the option of writing a subject line and this subject line is what will appear in the inbox of your recipient as the title of your email. On clicking on that subject line, the recipient will be able to read your email.


Email throttling is a delay you can define and schedule between each email sent. In other words, throttling is when a server controls the number of email addresses that get sent to an Email Service Provider (ESP). It is a method of stopping too many messages arriving into an inbox, especially from one sender, preventing spam and junk mail.

A transactional email is an email sent to someone automatically, after that person has carried out an action – such as making a purchase online, changing account details or subscribing to a newsletter. They are normally automated, but can also be sent manually.


Unsubscribe rate is a metric used by email marketers to see how many people have unsubscribed from the emailing lists they operate. The higher the unsubscribe rate, the more chance there is something wrong with the emails – and the more likely it is that a new approach is needed.


A welcome email is the first email a user will receive when they sign up to communications from a business or brand. This email is the equivalent of an “on-boarding” email, and will contain information about the subscription, the business and the products or services that the business sells.

Whitelisting an email address is adding that email address to a list of approved senders. Senders on your whitelist are senders who you believe are genuine and safe, as opposed to those on email blacklists who have a higher probability of being fraudulent.

The Google Workspace Marketplace is a platform where users can download apps for the Google Workspace. These apps can be used with things like Gmail, Google Docs, Google Sheets and more to make your work and personal life easier.