Email marketing glossary

Estimated reading time: 15 minutes

Email marketing is sprawling discipline—and with that size comes a significant number of terms and acronyms. Listening to email marketers speak using all the associated jargon sometimes sounds like listening to a totally different language. This glossary encompasses more than 100 of the terms you’ll hear as you get deeper into email marketing and also directs you to other parts of Jilt Learn where we dig deeper into those terms and see how to put them into action.

Jump to: A – F | G – L | M – R | S – Z

A – F

A/B testing

(Also known as: bucket testing, split testing) A method of comparing two versions of an email to see which performs better. Generally involves testing just one difference (e.g., a change in subject line) sent to equal-sized, random samples of an email list.

Abandonment rate

See: Cart abandonment rate


The area at the top of an email, generally encompassing what most users will see without scrolling. This part of the email is considered premium real estate because it displays as soon as the email is opened and, therefore, it is often filled with the most important content of the email.

Allow list

A list of email addresses, generally created by an individual email recipient, adding a domain or IP to a list of approved or safe senders. Users rarely make their own whitelist; instead, it’s created by their email service provider based on user actions, like adding an email address to their contacts or safe senders list, clicking the “not spam” button if an email winds up in spam, or creating a filter for a domain or email address to ensure it always goes to the inbox. See also: Blocklist


An email, or series of emails, sent out automatically when triggered by a customer action (e.g., abandoning a cart) or event (e.g., a customer’s birthday). One of the three major classifications of eCommerce email, along with broadcast and transactional.

Attributable revenue

eCommerce store revenue that can be directly credited to sales made via marketing emails.

Average order value (AOV)

The average amount a customer spends per transaction at an eCommerce store. Calculated by dividing total revenue from a defined period by the number of orders completed in that same period.


Former term for list of email addresses, domains, and/or IP addresses that should be regarded as spam. Term is being phased out in favor of blocklist.


A list containing email addresses, domains, and/or IP addresses that should be regarded as spam. These lists are maintained by email providers or third-parties and used to filter or block likely spam messages. (Test your domain or IP here to see if you’re on any blocklists.) See also: Allow list

Bounce rate

The percentage of emails sent that were returned to sender (or “bounced back”) by recipients’ email servers. Calculated for an individual email campaign by dividing emails bounced by emails sent. See also: Hard bounce; soft bounce


A single, one-off message sent to an entire email list or a segment of an email list. The most common types include sales announcements, newsletters, and company news. One of the three major classifications of eCommerce email, along with automation and transactional. See also: Newsletter

Bucket testing

See: A/B testing

California Consumer Privacy Act (CCPA)

A U.S. state law, effective as of January 1, 2020, that gives Californians the right to access and control how companies use their personal data.

Call-to-action (CTA)

A text link, image, or button in an email instructing and enticing a user to click through to take a specific action, such as buying a product or leaving a review.


An email, or coordinated series of emails, designed around a single goal (or cohesive set of goals). A campaign could be one broadcast email announcing a holiday sale, or a 10-email welcome series to introduce a customer to a company or a product. See also: Drip campaign; Series


A federal law, in effect as of 2003, that establishes standards, rules, and requirements for emails sent to U.S. recipients and/or sent by U.S. companies. The name is an acronym for Controlling the Assault of Non-Solicited Pornography And Marketing.

Canadian Anti-Spam Law (CASL)

A federal law, in effect as of 2014, that establishes standards, rules, and requirements for emails sent to Canadian residents and/or sent by Canadian companies or through Canadian servers.

Cart abandonment

The process whereby a customer adds products to a shopping cart but leaves the site before completing the entire checkout process. See also: Cart abandonment rate

Cart abandonment rate

The percentage of shopping carts that are “abandoned” by users before they complete the purchase. Calculated by taking the total number of abandoned carts and dividing by the sum of completed and abandoned carts. Industry-wide research generally finds abandonment rates are near 70 percent. See also: Cart abandonment recovery rate

Cart abandonment recovery email

An automated email, or series of emails, sent to a user that has put items in a shopping cart but did not complete the purchase. A highly-effective technique for recovering lost sales.

Cart abandonment recovery rate

The percentage of abandoned shopping carts an eCommerce store is able to recover by persuading a customer to return to finish the purchase. Calculated by taking the number of recovered carts and dividing by the total number of abandoned carts. See also: Cart abandonment rate

Churn rate

The percentage of subscribers who remove themselves or are removed from an email list via unsubscribing, a spam complaint, or a hard bounce (collectively known as “churn”). Calculated by adding unsubscribes, hard bounces, and spam complaints for an email and dividing by the total list size. Industry-wide research generally finds annual churn rates in the 25 to 30 percent range. 

Click-thru rate (CTR)

The percentage of subscribers who click on a link or button in an email. Calculated by dividing the total number of clicks (or unique clicks, for a more accurate measurement) by the number of emails delivered. CTR is one of the most popular email marketing metrics because high CTRs are an indication of a healthy email list and effective email content.

Click-to-open-rate (CTOR)

The percentage of subscribers who open an email and click a link or button in the email. Calculated by dividing the total clicks on an email by total opens. (Or, for a more accurate picture, unique clicks divided by unique opens.) CTOR is a useful metric to email content effectiveness (e.g., a high open rate but low click-to-open rate could indicate an effective subject line but ineffective email content). 

Complaint rate

The percentage of subscribers who mark an email as spam. Calculated by dividing the total spam complaints on an email by total emails delivered. Spam complaints are amongst the worst outcomes for a marketing email, as they can hurt future deliverability and sender reputation, and could even cause a domain or IP address to wind up on a blacklist. See also: Spam; Deliverability


Any subscriber, customer, or potential customer that has provided an email address to an eCommerce store. Includes those who have opted in to receive marketing emails, and those who have not but may still receive transactional emails.

Contact list

A list of email subscribers.

Conversion rate (CVR)

The percentage of email recipients who complete a desired action, such as making a purchase, leaving a product review, or following a brand on social media. Calculated by dividing the number of subscribers who took a desired action by total emails delivered. CVR is a direct indication of the effectiveness of an email campaign.


Promotion of a product or add-on closely related to the product a customer is purchasing or has purchased (e.g., a screen protector for a mobile phone). Cross-sells can be used alone in an automated email based on purchase behavior, or be incorporated into other emails. See also: Upsell

Customer acquisition cost (CAC)

The average cost, typically from marketing or sales efforts, to gain new customers for a store. Calculated by dividing total advertising spend by total new customers acquired over a defined period. CAC is an important metric to determine proper advertising budgets. See also: Subscriber acquisition cost, customer lifetime value

Customer lifetime value (CLTV)

See: Lifetime value


The measurement of how many sent emails actually make it to subscribers’ inboxes—meaning they were not blocked by an email provider and did not wind up in a spam folder. Deliverability can be affected by multiple factors including spam complaints, bounces, spam traps, open rates, and sender reputation.


A broadcast email that rounds up and/or summarizes information, sales, or links. It could include things like blog posts, user activity, transactions, or news. Digests can be personalized to a user (e.g., “A summary of your usage from June”) or sent to an entire list or a segment of a list (e.g., “Our new content for the week of August 12th”). See also: Newsletter

DomainKeys Identified Mail (DKIM)

An email authentication method designed to identify spoofed email addresses, which are often used to commit fraud. DKIM affixes a private cryptographic key, or “digital signature,” to an email, which allows the recipient’s server to verify who sent the message by matching the private key to a public key published by the sender. See also: Sender Policy Framework; Domain-based Message Authentication, Reporting & Conformance

Domain-based Message Authentication, Reporting & Conformance (DMARC)

An email authentication protocol that allows senders to indicate whether their emails are protected by Sender Policy Framework (SPF) and/or DomainKeys Identified Mail (DKIM), with instructions of what to do if the message does not pass either of those authentication methods (such as send to the spam folder or reject the email). See also: DomainKeys Identified Mail; Sender Policy Framework

Double opt-in

The process of requiring an email subscriber to confirm their intention to subscribe to an email list by clicking on a link in a confirmation email. The subscriber will only be added to the list after clicking on the confirmation email link. See also: Single opt-in

Drip campaign

An email campaign including multiple emails, sent at predetermined intervals, designed to gradually educate, onboard, and/or ultimately sell to a subscriber. See also: Campaign; Series

Dunning email

A transactional email used to notify customers about problems related to payment (e.g., the credit card on file for a recurring charge has expired).

Dynamic content

Email content that is automatically customized to a user based on their personal information, behaviors, or other defining characteristics. For example, a section of an email with recommended products based on a user’s purchase history or geographic location. See also: Merge tags

Email blast

A single, one-off broadcast email sent to a large group of recipients. This term now has a slightly negative connotation, as “blast” can indicate the email lacks proper segmentation or personalization.

Email client

The software used by a person to access their email. Examples of email clients include Microsoft Outlook and Apple Mail. Email clients also include webmail interfaces like Gmail or Yahoo Mail. 

Email service provider (ESP)

A service for receiving and sending email messages. ESP can refer to both the providers used by subscribers to receive email (e.g., Gmail or Yahoo Mail) and the providers used by companies to send emails (e.g., Jilt or… hmm… can’t think of any others 😉).

Emails delivered

A metric that shows the total numbers emails that reached subscribers’ mailboxes and, therefore, could possibly have been read by a recipient. Calculated by taking the total number of emails sent, then subtracting bounces.

Express consent

Explicit permission, voluntarily given by a user, to receive marketing email messages from a company. Express consent is required in many jurisdictions in order for companies to legally send marketing emails to customers. It is not required for transactional emails. See also: Implied consent


The bottom portion of an email where companies usually put an unsubscribe link and legal information. This section often also includes links to sections of an eCommerce website and social media.

From field

The displayed “from” name on an email. It appears in subscribers’ inboxes and serves as an important way to identify the brand behind the email. If a sender leaves the from field blank, their email address will be displayed.

G – L

General Data Protection Regulation (GDPR)

A law, in effect as of 2018, that establishes standards, rules, and requirements for emails sent to European Union residents and/or sent by E.U. companies. GDPR also encompasses data protection rules and gives people access to and control over their personal data.

Hard bounce

An email that is returned to sender for a permanent reason, such as an email address that no longer exists or an email server that has completely blocked delivery. Hard bounces can affect deliverability and email addresses that hard bounce should be removed from an email list entirely. See also: Bounce rate; Soft bounce

HTML email

An email created with HTML to include elements like colors, images, links, and other formatting. See also: Plain-text

Implied consent

Derived from a user taking an action that indicates a business interest in a company and, therefore, that the user is receptive to receiving email correspondence from that company. Business interest in a company could include buying a product or adding a product to a cart. With implied consent, users have not explicitly given the company permission to send marketing emails. See also: Express consent


A subscriber or customer who has stopped interacting with a brand. What constitutes “inactive” status can vary, but common indicators include a subscriber who has stopped opening or clicking emails, or a customer who has not made a purchase from an eCommerce store in a defined amount of time. Inactive subscribers and customers are targets for win-back emails; and, afterwards, if they remain inactive, should be purged from email lists. See also: Win-back emails

Lifecycle emails

Emails automatically sent at different points of the customer journey; a subset of automations. Pre-sale lifecycle emails include a welcome series to subscribers and cart abandonment emails; post-sale lifecycle emails include review requests and loyalty reward programs; and lapsed customer lifecycle emails include win-back emails.  See also: Automation

Lifetime value (LTV)

The average amount a customer will spend with an eCommerce store during their time as a customer. Calculated by multiplying the average number of purchases a customer makes in a year by the average purchase value—then multiplying the result by the average customer lifespan (in years). Lifetime value is a similar metric to subscriber lifetime value. See also: Subscriber lifetime value

List fatigue

A drop in email engagement metrics (open rate, click-through rate, conversion rate), which indicates that subscribers have begun losing interest in a company’s email list and no longer find the emails timely, relevant, or valuable.

List growth rate

The metric to measure how fast an email list is growing. Calculated by taking the number of new subscribers in a defined period (often a month or a quarter), subtracting the number of churned subscribers in that period, then dividing by the total number of email addresses on a list at the end of that period. A way to see whether list popularity is growing, and how fast new subscribers are outpacing churned subscribers.

List hygiene

The act of cleaning an email list to remove inactive and unengaged subscribers. A clean, engaged list can help to ensure inactive subscribers and/or spam traps don’t affect deliverability.

Loyalty/rewards emails

Automated emails updating a customer on their status, benefits, and offers for being a member of a loyalty, rewards, or VIP program. These emails are an excellent method of building customer relationships, incentivizing repeat purchases, and turning customers into brand advocates.

M – R

Mail user agent (MUA)

See: Email client

Mailing list

See: Contact list

Merge tags

A piece of code that allows a marketer to insert unique user information into an email (e.g., a merge tag like {{ customer.first_name }} would insert a subscriber’s first name into that spot in the email they receive). There are a number of different merge tag standards (Jilt, for example, uses Liquid.) See also: Dynamic content; Personalization

Milestone emails

Automated emails to a customer sent based upon a milestone in their personal life (e.g., their birthday) or a milestone with a brand (e.g., the one-year anniversary of their first purchase).


Broadcast emails generally featuring original content or a digest/round-up of content on the company’s website or other websites. Newsletters are generally a content marketing initiative; while they aren’t always focused on making a hard sell, they keep subscribers engaged, build brand loyalty, and can lead to more sales in the future.


See: Welcome email

Open rate

The percentage of subscribers who open an email. Calculated by taking emails opened and dividing by total emails delivered. (Or unique opens divided by emails delivered, to ensure subscribers who open an email multiple times don’t skew the results.) This is one of the most cited and studied email metrics.


Providing the option for subscribers to choose to receive fewer emails from a company, rather than outright unsubscribing.


The act of explicitly choosing to receive marketing emails from a company. A legal requirement for companies to send marketing emails in most jurisdictions; without an opt-in, a promotional email is spam. See also: Double opt-in, Single opt-in, Express consent


See: Unsubscribe

Order receipt

See: Receipt


The act of automatically adding information to an email unique to the recipient. While personalization can include using merge tags to include a name (e.g., “Hi Lauren, here’s a special deal just for you”), more advanced and effective personalization can include targeted cross-sells and upsells, milestone emails, cart abandonment emails, and onboarding guides based on purchases. Personalization is an increasingly effective and important aspect of email marketing. See also: Segmentation, Dynamic content


An email created in just text, featuring no colors, images, or other formatting. See also: HTML email

Preview text

A secondary line of text that appears after or underneath an email subject line in a customer’s inbox on many email clients. It is often used in tandem with the subject line to elaborate, clarify, entertain, and entice the subscriber to open. See also: Subject line

Privacy and Electronic Communications Regulations (PECR)

A law, in effect as of 2013, that establishes standards, rules, and requirements for emails sent to U.K. residents and/or sent by U.K. companies.

Privacy policy

A statement or legal document that discloses how a company will gather and use all data collected from subscribers.

Promotions tab

One of the optional organizational tabs implemented by Gmail in 2013 to automatically sort and separate inbox messages into different categories. Around one-third leave them enabled, and most eCommerce brand emails will be sorted into the Promotions tab. The advent of the Promotions tab caused a great deal of concern for marketers, however, it’s proven not to have a notable effect on email engagement.


Transactional emails sent to a customer right after a purchase. Receipts have some of the highest open rates of any emails.

Renewal notification

Transactional emails to let a customer know that a renewal, either automatic or manual, is coming up. Often sent as a series leading up to the renewal date. See also: Replenishment reminder

Replenishment reminder

An automated email or series of emails sent to remind the customer to reorder a consumable product they previously ordered that may be running out. See also: Renewal notification

Responsive design

A design technique that uses flexible layouts to ensure an email looks good regardless of a user’s screen size. It is now essentially a requirement for marketing emails, since modern internet users tend to access emails from multiple devices. 

Return on investment (ROI)

A measure of how much revenue emails are bringing in compared to the investment in those emails. Calculated by revenue generated by email marketing divided by the money invested into email marketing. (The result can then be multiplied by 100 to express as a percentage.) Email marketing famously has a high ROI; two frequently cited stats peg it at an average of 3,800 percent to 4,400 percent—in other words, $38 to $44 for every $1 spent.

Review/feedback request

An automated email asking a customer to review a recent purchase and/or their experience with the eCommerce store as a whole. This type of email is also used to ask customers for feedback (e.g., a survey about customer service or the overall shopping experience).

S – Z


The grouping of email subscribers into smaller sets based on information like geography (e.g., city, climate); demographics (e.g., age, gender); psychographics (e.g., values, interests); behaviors (e.g., engagement levels); or shopping activity (e.g., cart value). Segmentation is an extraordinarily effective technique for sending relevant emails to subscribers and can be thought of as “personalization at scale.” See also: Personalization

Send frequency

How often a brand sends emails to subscribers. It is a hotly-debated topic with no universally “correct” answer.

Sender Policy Framework (SPF)

An email authentication method used by mail servers to detect fraudulent sender addresses in emails. See also: Domain-based Message Authentication, Reporting & Conformance; DomainKeys Identified Mail

Sender Score

A score from zero to 100 that indicates an IP address’s reputation and deliverability, determined through a proprietary algorithm by email optimization company Return Path. It is analogous to a person’s credit score. See also: Deliverability


An email campaign including multiple emails, sent at predetermined intervals, designed to build a customer relationship or encourage the subscriber to act. Often used interchangeably with drip campaign. See also: Campaign; Drip campaign

Sharing/forwarding rate

The percentage of subscribers who click on a sharing or forwarding link in an email to send it to another person. Calculated by total clicks on the “share” link divided by emails delivered. Share rates are generally not high for eCommerce emails, as the primary calls-to-action in eCommerce emails are much more likely to focus on driving subscribers to make a purchase rather than to share. They are a useful metric to track for newsletters, however.

Shipping confirmation

A transactional email sent to subscribers to confirm a product has been shipped. It usually includes a tracking number.

Single opt-in

The process of adding a new subscriber to a list when they submit their email address via a form on an eCommerce site, without sending any type of additional confirmation email. See also: Double opt-in

Soft bounce

An email that is returned to sender for temporary reasons, such as a full inbox. Many email service providers will attempt to resend soft bounced emails. While email addresses that soft bounce should not be purged from an email list immediately, if an address continues to repeatedly soft bounce it can affect deliverability and should be purged. See also: Bounce rate; Hard bounce


Unsolicited bulk promotional emails sent without permission. 

Spam trap

A fraud management tool used by major Internet Service Providers to identify spammers. A spam trap is a “real” email address, often an old email address from a former customer, that spammers might have on a list they illegally gathered or scraped online. Emails sent to email addresses designated by ISPs as spam traps are a significant indicator that a company is sending spam (or low value emails to a list with poor list hygiene) and can have a serious detrimental effect on deliverability.

Split testing

See: A/B testing

Subject line

A single line of text, displayed in the inbox, that describes what the email is about and/or entices a subscriber to open the email to read more. See also: Preview text

Subscriber acquisition cost

The average cost of acquiring a new subscriber. Calculated by dividing total advertising spend by total new customers acquired over a defined period. It is an important metric for determining proper advertising budgets when paired with subscriber lifetime value. See also: Subscriber lifetime value; Customer acquisition cost

Subscriber lifetime value

The average amount a subscriber will spend with an eCommerce store as a direct result of email marketing during their time as a customer. Calculated by multiplying the average number of email-driven purchases a subscriber makes in a year by the average email-purchase value—then multiplying the result by the average subscriber lifespan (in years). See also: Lifetime value

Transactional email

A business-focused email sent out automatically based on a customer action (e.g., making a purchase or requesting a new password) that delivers vital information necessary to complete a transaction. One of the three major classifications of eCommerce email, along with broadcast and automation. A major distinction is that transactional emails are considered necessary for business purposes so they do not require an opt-in.

Triggered email

See: Automation


An action taken by a subscriber to stop receiving a company’s marketing emails. Under the laws in most jurisdictions, an easy method of unsubscribing must be offered in all marketing emails. This most often takes the form of an unsubscribe link in the email footer.

Unsubscribe rate

The rate at which people choose to unsubscribe from a list after a given email. Calculated by dividing the total number of unsubscribes by emails delivered. Sustained high unsubscribe rates could be an indication of a bad sending frequency or that customers are no longer finding emails relevant or valuable.


The promotion of an enhanced, higher-end, or improved version of a product a customer is purchasing or has purchased (e.g., trying to get a basic-tier subscriber to upgrade to gold-tier, or recommending a model of a computer with a faster processor). They can stand alone in their own automated emails, or be incorporated into other emails. See also: Cross-sell

Visual hierarchy

The order in which users process information in an email and mentally assign importance to its various elements. Visual hierarchy is used to inform a number of common email design patterns that take advantage of the way users process information to draw attention to specific pieces. See also: Above-the-fold

Welcome email

An automated email, or series of emails, sent to new subscribers or customers that serves as the start of their relationship with an eCommerce brand. Welcome emails can include a general greeting, an introduction of the store’s values and story, and/or a promotional coupon code for their next purchase. 


Former term for list of email addresses, generally created by an individual email recipient, adding a domain or IP to a list of approved or safe senders. Term is being phased out in favor of allow list.

Win-back email

An automated email, or series of emails, to re-engage inactive customers or subscribers. Win-back campaigns often feature a message saying something like “We miss you” and include an incentive to entice the customer to return to the store. Customers or subscribers that don’t become active again are often purged from the email list.