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Retention Marketing
Glossary A-Z

A complete A-Z glossary of retention marketing and eCommerce terms, covering email, SMS, push notifications, Klaviyo, Shopify, deliverability, and more.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A

Automation

In retention marketing, automations are pre-built message sequences that send automatically based on a subscriber’s behavior or actions. In Klaviyo, these are known as Flows. Examples include a welcome series that triggers when someone signs up, or an abandoned cart email that sends when a shopper leaves without purchasing.

A/B Testing

A method of testing two versions of an email or SMS to see which performs better. You might test subject lines, send times, content, or CTAs. Results inform smarter decisions across both campaigns and flows.

Acquisition Cost

The total amount spent to acquire a single new customer, calculated by dividing total marketing spend by the number of new customers gained. Retention marketing exists partly to maximize the return on that initial acquisition investment.

Active Subscriber

A contact who has opted in to receive marketing messages and has engaged within a defined time window, typically 30, 60, or 90 days. Sending primarily to active subscribers protects deliverability and improves overall list performance.

Add to Cart Rate

The percentage of store visitors who add at least one product to their cart. A low add-to-cart rate often signals a product, pricing, or UX issue rather than a retention problem.

Advanced Segmentation

The practice of dividing your audience into highly specific groups based on behavior, purchase history, location, engagement level, or custom properties. More precise segments lead to more relevant messaging and higher conversion rates.

 

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AOV (Average Order Value)

The average amount spent per order, calculated by dividing total revenue by number of orders. Increasing AOV through upsells, bundles, and cross-sells is one of the highest-leverage moves in eCommerce retention.

Attribution Model

A set of rules that determines how revenue credit is assigned to a marketing channel or message after a customer converts. Klaviyo uses a last-touch attribution model by default, with a configurable window after an email open or click. Choosing the right attribution model is important for accurately measuring the true impact of your email and SMS program.

Average Revenue Per Recipient (ARPR)

The average revenue generated per contact who received a campaign or flow message. ARPR is a useful metric for comparing the effectiveness of different sends without being skewed by list size.

B

Back-in-Stock Flow

An automated sequence that notifies subscribers when a product they showed interest in is available again. Customers sign up to be alerted, and Klaviyo triggers the message automatically once stock is restored. A high-intent flow that converts well because the customer already wants the product.

Birthday Flow

An automated sequence triggered by a subscriber’s birthday date stored in Klaviyo. Typically used to send a personalized offer or discount around the customer’s birthday. A simple but effective way to drive repeat purchases and strengthen customer relationships.

Behavioral Trigger

An action taken by a subscriber that kicks off an automated flow or message. Common behavioral triggers include viewing a product, adding to cart, making a purchase, or clicking a specific link. The more precisely you define triggers, the more relevant your messaging becomes.

Benchmark

A reference point used to measure the performance of your email or SMS program. Benchmarks can be industry averages for open rates, click rates, or revenue per email, or your own historical performance used as a baseline for improvement.

Bounce Rate (Email)

The percentage of emails that could not be delivered to the recipient’s inbox. Split into hard bounces (permanent delivery failures) and soft bounces (temporary issues). A high bounce rate signals list hygiene problems and can damage sender reputation.

Brand Affinity

The degree to which a customer feels a personal connection to a brand beyond just purchasing from it. Customers with high brand affinity are more likely to buy repeatedly, refer others, and engage with your emails and SMS. Building brand affinity is a core goal of retention marketing.

Browse Abandonment

When a visitor views a product page but leaves without adding anything to their cart. In Klaviyo, this behavior can trigger an automated flow that follows up with the products they browsed, nudging them back toward a purchase.

Business-to-Consumer (B2C)

A business model where a company sells products or services directly to individual consumers rather than other businesses. Most DTC eCommerce brands operate on a B2C model, and retention marketing strategies are primarily designed around the B2C purchase cycle.

C

Campaign

A one-time email or SMS send to a defined segment of your list. Unlike flows, campaigns are manually scheduled and sent to a specific audience at a specific time. Used for promotions, product launches, seasonal offers, and newsletters.

Cart Abandonment Flow

An automated sequence triggered when a shopper adds products to their cart but leaves without completing the purchase. One of the highest-revenue flows in eCommerce, typically consisting of 2 to 4 emails and optionally an SMS, sent over 24 to 48 hours.

 

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Cart Abandonment Rate

The percentage of shoppers who add items to their cart but do not complete the purchase. Industry average sits around 70%, making cart abandonment one of the biggest revenue leakage points in eCommerce.

Checkout Abandonment Flow

Similar to cart abandonment, but triggered specifically when a shopper reaches the checkout page and leaves without completing payment. Higher purchase intent than cart abandonment, which typically makes this flow convert at a higher rate.

Churn Rate

The percentage of customers or subscribers who stop engaging with or purchasing from your brand over a given period. High churn is a signal that retention efforts are underperforming and that post-purchase experience needs improvement.

Click Rate

The percentage of delivered emails where at least one link was clicked. Click rate measures how compelling your email content and CTAs are beyond just the subject line.

Click-to-Open Rate (CTOR)

The percentage of people who clicked a link out of those who actually opened the email. CTOR isolates the performance of your email body and CTA from subject line performance, making it a more precise engagement metric than click rate alone.

Customer Lifetime Value (CLTV)

The total revenue a customer is expected to generate throughout their entire relationship with your brand. CLV is one of the most important metrics in retention marketing, as increasing it even slightly has a compounding effect on overall business revenue.

 

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Cohort Analysis

A method of grouping customers by a shared characteristic or time period, such as the month they first purchased, and tracking their behavior over time. Cohort analysis helps identify patterns in retention, repeat purchase rates, and churn across different customer groups.

Conditional Split

A logic branch inside a Klaviyo flow that divides subscribers into different paths based on specific conditions, such as whether they have made a purchase, are VIP customers, or opened a previous email. Conditional splits enable more personalized and relevant messaging within a single flow.

Consent (Marketing Consent)

The explicit permission a contact gives to receive marketing communications via email or SMS. Consent must be properly collected and documented to comply with regulations like GDPR and CAN-SPAM. Sending to contacts without valid consent can result in spam complaints and legal issues.

Conversion Rate

The percentage of recipients who completed a desired action after receiving a message, such as making a purchase or signing up. Conversion rate is the ultimate measure of whether your retention marketing is driving real business outcomes.

Cross-sell

The practice of recommending complementary or related products to a customer based on what they have already purchased or are currently viewing. Cross-sells can be embedded in post-purchase flows, campaign emails, or product recommendation blocks.

Customer Retention

The ability of a brand to keep existing customers coming back to purchase again over time. Retention marketing is the discipline built around improving this metric through email, SMS, personalization, and lifecycle strategies.
D

Data Layer

A structured data object on a website that stores and passes information about user behavior, events, and transactions to marketing and analytics tools. In eCommerce, the data layer is what enables platforms like Klaviyo to track actions such as product views, cart updates, and purchases.

Dedicated IP

A unique sending IP address used exclusively by one sender. Unlike shared IPs, a dedicated IP means your sender reputation is built solely on your own sending behavior. Typically recommended for high-volume senders who want full control over their deliverability.

Dedicated Sending Domain

A custom domain used exclusively by your brand to send marketing emails, separate from your main business domain. Setting up a dedicated sending domain protects your primary domain’s reputation, improves deliverability, and is a recommended step when onboarding to Klaviyo or migrating from another ESP.

Deliverability

The ability of your emails to successfully reach the recipient’s inbox rather than landing in spam or being blocked entirely. Deliverability is influenced by sender reputation, list hygiene, engagement rates, authentication setup, and sending infrastructure.

 

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Delivery Rate

The percentage of sent emails that were successfully accepted by the recipient’s mail server, meaning they did not hard or soft bounce. Delivery rate is a baseline deliverability metric, though a high delivery rate does not guarantee inbox placement as emails can still land in spam.

Double Opt-in

A two-step subscription process where a new subscriber confirms their email address by clicking a link in a confirmation email before being added to your list. Double opt-in produces a smaller but higher-quality list with better engagement and fewer spam complaints.

DTC (Direct-to-Consumer)

A business model where a brand sells its products directly to end consumers, bypassing wholesalers, retailers, or third-party marketplaces. Most Shopify-based eCommerce brands operate DTC, making owned channels like email and SMS especially valuable.

Dynamic Content

Email or SMS content that automatically changes based on the recipient’s data, behavior, or segment. Examples include showing different product recommendations, offers, or messaging depending on whether a customer is a first-time buyer or a VIP.

Dark Mode

A display setting on email clients and devices that switches the color scheme from light backgrounds with dark text to dark backgrounds with light text. Emails that are not optimized for dark mode can render with invisible text or broken visuals for a significant portion of recipients, making dark mode testing an important part of email design.
E

Email List

The database of contacts who have opted in to receive email communications from your brand. List quality, size, and engagement level directly impact the performance and deliverability of your email program.

Email Service Provider (ESP)

A platform used to build, send, and manage email and SMS marketing. Klaviyo, Mailchimp, and Omnisend are examples of ESPs commonly used in eCommerce. The choice of ESP significantly affects what you can do with segmentation, automation, and data.

Engagement Rate

A measure of how actively your subscribers interact with your messages, typically combining open rates, click rates, and conversion data. High engagement signals a healthy list and improves deliverability, while low engagement can indicate the need for list cleaning or re-engagement campaigns.

Event-based Trigger

A specific action or event, such as a purchase, a refund, or a product review, that automatically starts a flow or sends a message in your ESP. Event-based triggers allow for highly timely and relevant communication tied directly to customer behavior.

Embed Form​

A signup form that is built directly into a page on your website rather than appearing as a popup or overlay. Embed forms work well in footers, blog posts, and dedicated landing pages, capturing subscribers who are actively browsing your content.

Email Marketing

The practice of using email to communicate with customers and prospects, drive repeat purchases, and build long-term brand relationships. For eCommerce brands, email is consistently the highest-ROI owned channel, enabling automated lifecycle messaging, promotional campaigns, and personalized communication at scale without relying on paid media or algorithms.

 

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F

First Purchase Flow

An automated sequence triggered when a customer makes their very first order. Designed to welcome new buyers, set expectations, and encourage a second purchase. The first purchase flow is critical for converting one-time buyers into repeat customers.

First-party Data

Data collected directly from your own customers and subscribers through your website, email list, purchase history, and surveys. First-party data is more accurate, privacy-compliant, and valuable than third-party data, and is the foundation of effective retention marketing.

Flow (Klaviyo)

Klaviyo’s term for an automated sequence of emails and SMS messages triggered by subscriber behavior or events. Flows run continuously in the background and are the primary driver of automated revenue in Klaviyo-based retention programs.

 

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Frequency Capping

A rule that limits how many messages a contact can receive within a defined time period. In Klaviyo this is known as Smart Sending. Frequency capping prevents over-messaging, reduces unsubscribe rates, and protects sender reputation.

Flyout Form

A signup form that slides in from the side or bottom of the screen as a visitor browses your website. Less disruptive than a full popup, flyout forms are a good middle ground between visibility and user experience, and typically convert well on mobile.

Full Page Popup

A signup form that takes over the entire screen when triggered, blocking all other content until the visitor submits or closes it. Full page popups are the most aggressive lead capture format and can achieve high conversion rates but should be used carefully to avoid negatively impacting user experience and SEO.

Fulfillment

The process of receiving, packing, and shipping a customer’s order. While not a retention marketing term directly, fulfillment speed and accuracy significantly impact post-purchase experience, review scores, and the likelihood of a customer buying again.
G

GDPR

A European Union regulation that governs how businesses collect, store, and use personal data. For email and SMS marketers, GDPR requires explicit consent before sending marketing communications to contacts in the EU, along with clear opt-out mechanisms.

Global Suppression List

A master list of contacts who have unsubscribed, bounced, or marked emails as spam, and who should never be contacted across any list or campaign. Maintaining an accurate global suppression list is essential for compliance and deliverability.
H

Hard Bounce

A permanent email delivery failure caused by an invalid or non-existent email address. Hard bounces should be removed from your list immediately as repeatedly sending to them damages sender reputation and deliverability.

Health Score (List)

A measure of the overall quality and engagement level of your email list. A healthy list has a high ratio of active, engaged subscribers, low bounce rates, and minimal spam complaints. Regular list cleaning is the primary way to maintain a strong health score.

Historical Data Migration

The process of transferring past customer data including purchase history, email engagement, and behavioral data from one platform to another during an ESP migration. Preserving historical data ensures segmentation, flows, and personalization work correctly from day one on the new platform.
I

Identification Rate

The percentage of anonymous website visitors that can be matched to a known contact in your ESP. A higher identification rate means more visitors can be enrolled in behavioral flows like browse abandonment or cart abandonment, directly increasing recoverable revenue.

Inactive Subscriber

A contact who has not opened, clicked, or engaged with your emails within a defined time window, typically 90 to 180 days. Inactive subscribers should be moved into a re-engagement flow or suppressed to protect deliverability and list health.

Integrations (ESP)

The connections between your ESP and other tools in your tech stack, such as Shopify, loyalty programs, review platforms, or helpdesk software. Integrations allow data to flow between systems, enabling richer segmentation and more personalized automation.

IP Warmup

The process of gradually increasing email sending volume from a new IP address to build a positive sender reputation with inbox providers. Sending too much too fast from a cold IP can trigger spam filters, so warmup is done in structured increments over several weeks.

Image Based Email

An email built primarily or entirely from images rather than HTML text. While visually flexible, image based emails are problematic for deliverability because spam filters cannot read image content, and they display as blank for subscribers who have images disabled by default.

Inbox Providers

The companies that operate email inbox services and determine whether your messages land in the inbox, promotions tab, or spam folder. Major inbox providers include Gmail, Apple Mail, Outlook, and Yahoo. Each applies its own filtering algorithms and deliverability rules.
J

Journey Mapping

The process of visualizing the full lifecycle of a customer, from first awareness through purchase, retention, and loyalty. In retention marketing, journey mapping helps identify the right touchpoints, messages, and timing for each stage of the customer relationship.
K

Klaviyo

An email and SMS marketing platform built specifically for eCommerce. Klaviyo integrates natively with Shopify and other platforms, enabling deep segmentation, behavioral automation, and revenue tracking. It is the most widely used ESP among DTC brands.

 

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KPI (Key Performance Indicator)

A measurable metric used to evaluate the performance of your marketing program against a specific goal. Common retention marketing KPIs include open rate, click rate, revenue per email, CLV, repeat purchase rate, and churn rate.
L

Landing Page

A standalone web page designed to convert visitors coming from a specific source, such as an email campaign or SMS. In retention marketing, landing pages are often used for promotions, product launches, or lead capture forms.

Lead Capture

The process of collecting contact information, typically an email address or phone number, from a potential customer. Common lead capture methods include popups, embedded forms, landing pages, and gated content.

List Cleaning

The process of removing invalid, inactive, or unengaged contacts from your email list. Regular list cleaning improves deliverability, engagement rates, and sender reputation, and reduces the cost of sending to contacts who will never convert.

List Growth Rate

The rate at which your email or SMS list is growing over a given period, factoring in new subscribers minus unsubscribes and bounces. A healthy list growth rate ensures your audience is expanding faster than it is churning.

List Hygiene

The ongoing practice of maintaining a clean, engaged, and compliant email list. List hygiene includes removing hard bounces, suppressing inactive subscribers, and ensuring all contacts have valid consent. Poor list hygiene is one of the most common causes of deliverability problems.

List Migration

The process of moving your subscriber list from one ESP to another. A successful list migration preserves consent records, suppression lists, tags, and custom properties to ensure continuity of your marketing program on the new platform.

Low in Stock Flow

An automated sequence that alerts subscribers when a product they have shown interest in is running low on inventory. Creates urgency and drives purchases by tapping into scarcity, particularly effective for high-demand or limited-edition products.

Light Mode

The default display setting on most email clients and devices, showing dark text on a light or white background. When designing emails, light mode is typically the baseline, but designs should always be tested in both light and dark mode to ensure they render correctly for all recipients.
M

Mailchimp

One of the most widely used email marketing platforms globally, popular among small businesses and beginners. While Mailchimp offers basic email automation and campaign tools, most scaling DTC eCommerce brands migrate to Klaviyo for its deeper Shopify integration, behavioral segmentation, and revenue tracking capabilities.

Marketing Automation

The use of software to automatically execute marketing actions based on predefined rules, triggers, or schedules. In eCommerce, marketing automation covers everything from welcome flows and abandoned cart sequences to post-purchase follow-ups and re-engagement campaigns.

Metrics

Quantifiable measures used to track and evaluate the performance of your marketing program. In retention marketing, key metrics include open rate, click rate, conversion rate, revenue per email, unsubscribe rate, and customer lifetime value.

MMS (Multimedia Messaging Service)

A type of SMS message that includes media such as images, GIFs, or short videos. MMS messages typically have higher engagement than plain text SMS but cost more to send. Used in eCommerce for product showcases, promotional visuals, and brand storytelling.

Mobile Optimization

The practice of ensuring your emails and landing pages render correctly and perform well on mobile devices. Given that the majority of emails are opened on mobile, poor mobile optimization directly impacts click rates and conversions.

Multi-channel Retention

A retention strategy that engages customers across more than one owned channel, typically combining email, SMS, and push notifications. Multi-channel programs outperform single-channel approaches by reaching customers through their preferred medium at the right moment.

Multi-step Flow

An automated flow that contains more than one message, sent across a sequence of delays and conditions. Most effective flows in Klaviyo are multi-step, such as a 3-email abandoned cart sequence or a 5-email welcome series.

Migration

The process of moving your email and SMS marketing program from one ESP to another. A full migration includes transferring subscriber lists, consent records, suppression lists, flow logic, templates, and historical data to ensure continuity on the new platform.
N

Net Promoter Score (NPS)

A customer satisfaction metric that measures how likely customers are to recommend your brand to others, on a scale of 0 to 10. NPS surveys are often sent via post-purchase email flows and provide a direct signal of customer loyalty and retention health.

Newsletter

A regularly scheduled email campaign sent to your subscriber list, typically containing brand updates, editorial content, product highlights, or curated offers. Newsletters are a core tool for maintaining ongoing engagement with your audience between promotional campaigns.
O

Omnichannel Marketing

A customer experience strategy that delivers consistent, connected messaging across all touchpoints including email, SMS, push notifications, paid ads, and on-site interactions. Unlike multi-channel marketing, omnichannel focuses on integrating these channels into a unified customer experience.

Omnisend

An email and SMS marketing platform designed for eCommerce, often considered an alternative to Klaviyo. Omnisend offers automation, segmentation, and multi-channel messaging, and is particularly popular among brands using WooCommerce or BigCommerce.

Onboarding Flow

An automated sequence triggered when a new customer makes their first purchase or a new subscriber joins your list. Designed to introduce the brand, set expectations, and guide the customer toward their next action, whether that is a second purchase, a loyalty program signup, or a product review.

Open Rate

The percentage of delivered emails that were opened by the recipient. Open rate is a measure of subject line effectiveness and sender reputation, though it has become less reliable as a standalone metric since Apple’s Mail Privacy Protection inflates open data for iOS users.

Opt-in

The action of a contact giving explicit permission to receive marketing communications from your brand via email or SMS. A valid opt-in is required for compliant marketing and is the foundation of a healthy, engaged list.

Opt-out

The action of a contact withdrawing their consent to receive marketing communications. Every email and SMS must include a clear and easy opt-out mechanism. Processing opt-outs promptly is both a legal requirement and a deliverability best practice.
P

Personalization

The practice of tailoring email and SMS content to individual recipients based on their data, behavior, or preferences. Personalization ranges from using a subscriber’s first name in a subject line to dynamically showing different products, offers, or messaging based on purchase history.

Popup

An on-site form that appears over page content, typically used to capture email addresses or phone numbers in exchange for a discount or incentive. Popups are one of the most effective list growth tools in eCommerce when designed and timed well.

Post-purchase Flow

An automated sequence triggered after a customer completes an order. Used to confirm the purchase, set delivery expectations, request a review, introduce loyalty programs, and encourage a second purchase. A well-built post-purchase flow is one of the strongest drivers of repeat purchase rate.

 

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Pre-built Flow

A ready-made automation template provided by an ESP like Klaviyo that can be activated and customized without building from scratch. Pre-built flows cover common use cases such as welcome series, abandoned cart, and post-purchase sequences.

Preview Text

The short snippet of text that appears in the inbox below or beside the subject line before the email is opened. Preview text acts as a second subject line and has a significant impact on open rates when used strategically rather than left to default to the first line of email body copy.

Price Drop Flow

An automated sequence that notifies subscribers who have shown interest in a product when its price is reduced. Highly effective for recovering hesitant shoppers who were interested but held back due to cost.

Product Recommendation

A personalized suggestion of products shown to a customer based on their browsing history, past purchases, or behavior. Product recommendations can be embedded in email flows and campaigns using dynamic content blocks to increase relevance and AOV.

Profile (Klaviyo)

A record in Klaviyo representing a single contact, containing their email address, phone number, consent status, custom properties, and full activity history. Every subscriber, customer, or site visitor that Klaviyo identifies becomes a profile.

Property (Klaviyo)

A data attribute stored on a Klaviyo profile or event that can be used for segmentation, personalization, and flow logic. Properties can include anything from first name and birthday to loyalty tier, last purchase date, or custom tags passed from Shopify.

Push Notification

A short message delivered directly to a user’s browser or mobile device, even when they are not actively on your website. Push notifications are used in eCommerce for abandoned cart reminders, back-in-stock alerts, and promotional offers, and work best as part of a broader multi-channel retention strategy.

 

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Predictive Analytics

The use of historical data and machine learning to forecast future customer behavior. In Klaviyo, predictive analytics powers features like predicted next order date, predicted CLV, and churn risk scores, enabling marketers to act on likely future behavior before it happens.
Q

Quiet Hours (SMS)

A setting that restricts SMS messages from being sent during late night or early morning hours, typically between 9pm and 9am in the recipient’s local time zone. Quiet hours are both a compliance requirement in many regions and a best practice for avoiding opt-outs caused by poorly timed messages.
R

Re-engagement Campaign

A one-time email or SMS campaign sent to inactive subscribers with the goal of winning back their attention before they are removed from the active list. Typically includes a compelling offer or a simple “are you still interested” message with a clear CTA.

Re-engagement Flow

An automated sequence triggered when a subscriber has not opened or clicked any emails within a defined period, typically 60 to 90 days. The flow attempts to reactivate the contact through a series of messages, and automatically suppresses those who remain unresponsive.

Repeat Purchase Rate

The percentage of customers who make more than one purchase from your store within a given time period. Repeat purchase rate is one of the most direct indicators of retention marketing effectiveness and overall customer loyalty.

 

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Replenishment Flow

An automated sequence triggered when a customer is likely running low on a consumable product they previously purchased. Based on average usage rates and purchase intervals, replenishment flows prompt customers to reorder before they run out, reducing churn and increasing LTV.

Retention Marketing

The discipline of using owned channels such as email, SMS, and push notifications to keep existing customers engaged, encourage repeat purchases, and maximize customer lifetime value. Retention marketing is typically more cost-effective than acquisition because it targets people who have already shown intent or made a purchase.

Revenue Attribution

The process of assigning revenue credit to a specific marketing channel, campaign, or flow based on customer actions. In Klaviyo, revenue attribution uses a defined window after a click or open to connect a purchase back to the email or SMS that influenced it.

Revenue Per Email (RPE)

The average revenue generated per email sent, calculated by dividing total email-attributed revenue by the number of emails delivered. RPE is one of the most useful metrics for comparing the commercial impact of different campaigns and flows.

Review Request Flow

An automated sequence sent after a customer receives their order, asking them to leave a product or store review. Review request flows are typically integrated with review platforms like Okendo, Yotpo, or Loox and are a key driver of social proof and repeat purchase behavior.

RFM (Recency, Frequency, Monetary)

A customer segmentation model that scores contacts based on how recently they purchased, how often they buy, and how much they spend. RFM segmentation is widely used in retention marketing to identify VIP customers, at-risk buyers, and lapsed customers who need re-engagement.
S

Sender Domain

The domain used to send your marketing emails, typically configured as a subdomain of your main website such as email.yourbrand.com. A properly authenticated sender domain with SPF, DKIM, and DMARC records is a foundational requirement for good deliverability.

Sender Reputation

A score assigned to your sending domain and IP address by inbox providers based on your sending behavior over time. Factors include engagement rates, spam complaints, bounce rates, and sending consistency. A strong sender reputation is the single biggest factor in whether your emails land in the inbox or spam.

Segmentation

The practice of dividing your subscriber list into groups based on shared characteristics, behaviors, or data points. Effective segmentation ensures the right message reaches the right person at the right time, improving engagement, conversions, and unsubscribe rates.

Sequences

A sequence of emails sent in a defined order over a period of time, either as part of an automated flow or a multi-send campaign. Email series are used for onboarding, education, promotions, and nurturing customers through a specific journey.

Shopify

The leading eCommerce platform for DTC brands, used to build and manage online stores. Shopify integrates natively with Klaviyo, enabling real-time syncing of customer data, purchase events, and product information that powers segmentation and automation.

 

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Single Opt-in

A subscription process where a contact is added to your list immediately after submitting their email or phone number, without a confirmation step. Single opt-in grows lists faster than double opt-in but can result in lower quality contacts and a higher risk of spam complaints.

SMS Compliance

The set of legal and regulatory requirements governing how brands collect consent, send messages, and handle opt-outs for SMS marketing. Key regulations include TCPA in the US and GDPR in the EU. Non-compliance can result in significant fines and carrier filtering.

SMS Keyword

A specific word that a customer can text to a shortcode or number to trigger an automated response or opt into an SMS list. Common examples include JOIN, STOP, or promotional keywords like SAVE20. Keywords are a simple and effective list growth tool for SMS.

SMS Marketing

The use of text messages to communicate with customers and drive eCommerce revenue. SMS has significantly higher open and click rates than email and works best as part of a multi-channel retention strategy alongside email, particularly for time-sensitive offers and abandoned cart recovery.

 

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Soft Bounce

A temporary email delivery failure caused by issues such as a full inbox or a server being unavailable. Unlike hard bounces, soft bounces do not necessarily indicate an invalid address, but contacts that consistently soft bounce should eventually be suppressed.

Spam Complaint Rate

The percentage of recipients who mark your email as spam. A rate above 0.1% is considered problematic by most inbox providers and can severely damage sender reputation. High spam complaint rates are usually caused by poor list hygiene, irrelevant content, or sending to unengaged contacts.

Spam Trap

An email address used by inbox providers and anti-spam organizations to identify senders with poor list hygiene practices. Sending to spam traps signals that you are not properly managing your list and can result in blacklisting or inbox placement issues.

Split Testing

In Klaviyo, split testing can be applied to both campaigns and flows to test subject lines, content, send times, and flow paths against each other to identify what drives better performance.

Subject Line

The first line of text a recipient sees in their inbox before opening an email. Subject lines have the single biggest impact on open rates and should be clear, relevant, and compelling without being misleading or triggering spam filters.

Suppression List

A list of contacts who should not receive marketing communications, including unsubscribes, hard bounces, spam complainers, and manually suppressed addresses. Maintaining an accurate suppression list is essential for compliance and deliverability.

Sunset Policy

A defined strategy for suppressing or removing subscribers who have not engaged with your emails over a set period, typically 90 to 180 days. A sunset policy keeps your active list clean, protects deliverability, and ensures you are only paying to send to contacts who have a realistic chance of converting.
T

Transactional Email

An automated email triggered by a specific customer action, such as an order confirmation, shipping notification, or password reset. Unlike marketing emails, transactional emails are expected by the recipient and typically achieve very high open rates. They can also include subtle marketing elements where permitted.

Trigger

A specific event or condition that automatically starts a flow or sends a message in your ESP. Triggers can be behavioral such as a product view or purchase, time-based such as a birthday or subscription anniversary, or data-driven such as a change in a profile property.

Two-way SMS

An SMS setup that allows customers to reply to your messages and receive a response, either automated or from a human. Two-way SMS improves customer experience and can be used for preference collection, support, surveys, and conversational marketing.
U

Unsubscribe Rate

The percentage of recipients who opt out of your email or SMS list after receiving a message. A healthy unsubscribe rate is generally below 0.2% per send. Elevated unsubscribe rates typically signal that messaging is irrelevant, too frequent, or being sent to the wrong audience.

Upsell

The practice of encouraging a customer to purchase a higher-value version of a product or add complementary items to their order. Upsells can be delivered through post-purchase flows, product recommendation blocks in emails, or dedicated campaign sends.

UTM Parameters

Tags added to URLs in your emails and SMS messages that allow analytics platforms like Google Analytics to track where traffic and conversions are coming from. Proper UTM setup is essential for accurate attribution and understanding which campaigns and flows are driving revenue.

V

VIP Flow

An automated sequence triggered when a customer reaches a defined VIP threshold, such as a total spend amount or number of orders. Used to acknowledge and reward high-value customers, strengthen loyalty, and encourage continued purchasing behavior.

VIP Segment

A defined group of your highest-value customers, typically identified by spend, purchase frequency, or loyalty status. VIP segments are used to send exclusive offers, early access campaigns, and personalized communications that reinforce the relationship with your most important buyers.
W

Webhook

A mechanism that automatically sends data from one platform to another in real time when a specific event occurs. In eCommerce, webhooks are used to pass data between Shopify, Klaviyo, and other tools, enabling triggers, profile updates, and integrations without manual data transfers.

Welcome Flow

An automated sequence triggered when someone subscribes to your email or SMS list for the first time. The welcome flow is typically the highest-performing flow in any Klaviyo account, as subscribers are at peak interest when they first sign up. It introduces the brand, delivers any signup incentive, and guides the new subscriber toward a first purchase.

 

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Win-Back Flow

An automated sequence targeting customers who have not purchased within a defined period, typically 90 to 180 days. The goal is to re-engage lapsed buyers with compelling offers, product updates, or personalized messaging before they are lost permanently.
Z

Zero-party Data

Data that a customer intentionally and proactively shares with a brand, such as preferences, interests, or purchase intentions collected through quizzes, surveys, or preference centers. Zero-party data is the highest quality data available because it comes directly from the customer and requires no inference or tracking.

 

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