The Ultimate List of 125+ Email Marketing Terms (Glossary)

Email marketing has its own unique language. Words like "allowlist" and "IP warming" can be confusing and overwhelming, especially for beginners.

This guide defines and explains 125+ email marketing terms you might come across. Understanding these terms will help you leverage the benefits of email marketing and improve your skills as a marketer.

Let’s dive into the definitions!

125+ Email Marketing Terms and Lingo Defined

With more than 125 entries, you'll be ready to impress your colleagues with your newfound knowledge of email marketing basics. Each term comes with a straightforward explanation of its meaning and importance.

A/B Testing

A/B testing is a powerful technique for optimizing your emails. It involves testing different versions of an email to see which one performs better. You can test subject lines, content, calls to action (CTA), and more.

Abandoned Cart Email

When a shopper adds items to their online cart but doesn't buy, an abandoned cart email reminds them to complete the purchase. These emails serve as reminders and can be very effective at recovering lost sales and boosting revenue.

Most ecommerce platforms track abandoned cart emails and allow you to send email or other messaging to help bring people back to complete the checkout process.

Acceptable Spam Report Rate

The acceptable spam report rate is the percentage of emails that can be marked as spam before it starts to hurt your sender reputation.

Services like Gmail let users report emails as spam. A good rate is under 0.1%. Anything higher looks suspicious and may cause some email service providers to handle emails from you differently. Your account with your email marketing platform could even be suspended.

Acceptance Rate

This is the percentage of emails a server agrees to take and try to deliver. A high acceptance rate is a good sign that your emails are not being flagged as spam. Maintaining a clean list and sending high-quality content can help ensure a high acceptance rate.

Allowlist

An allowlist, also known as a safelist or whitelist, is a list of approved or trusted email addresses or domains. Ask your recipients to place you in their allowlist to improve your deliverability and increase the chances of your emails reaching the inbox.

AMP Emails

Accelerated Mobile Pages (AMP) make emails fast-loading and mobile-friendly. This type of interactive email allows users to engage with content directly within the email. For example, they can fill out forms, make purchases, or book appointments without leaving the email client.

Apple Mail Privacy Protection

A tool introduced by Apple in iOS 15 that hides user IP addresses from email senders. This feature prevents email senders from using tracking pixels to gather information about email opens and IP addresses. It can impact email marketers who rely on open rates as a key performance metric.

Authentication Protocols

Email authentication protocols prove an email really comes from the listed domain. DKIM and DMARC are the most common protocols to confirm senders' identities. The goal of authentication protocols is to prevent email spoofing and phishing.

Autoresponder

Autoresponders automatically send pre-written emails when triggered. They give instant, relevant replies to actions such as signing up for a mailing list or buying an item. For instance, you can create an autoresponder to confirm a user's purchase and explain the next steps (such as shipping tracking details).

Bayesian Filter

Bayesian filters use advanced statistics to classify spam. They "learn" from user spam reports to improve over time. They do this by looking for cues like subject line keywords, sender IP address or domain, and other email content.

You may see senders trying to get around Bayesian filters by deliberately misspelling words, using similar letters or characters to impersonate legitimate domains, or using images instead of text.

Behavioral Emails

Behavioral emails are triggered by specific actions or behaviors taken by a user, such as abandoning a shopping cart or browsing a particular product category. These highly targeted emails can be very effective in driving engagement and boosting conversions.

Brand Indicators for Message Identification (BIMI)

Brand Indicators for Message Identification (BIMI) confirm legitimate branding. BIMI verifies that logos match actual companies. This can improve open rates and instill trust in recipients.

Blacklist

A blacklist is a list of IP addresses or domains that are known to send spam. Email providers block all messages from blacklisted senders. Getting on blacklists severely damages delivery, making it nearly impossible for your messages to reach the inbox.

Blocklist

A blocklist is simply another name for a blacklist. Senders on blocklists have their emails automatically filtered by receivers. This term is favored in the modern world, similar to how "allowlist" is replacing "whitelist."

Bounce Rate

Bounces happen when emails fail to deliver. The bounce rate represents the percentage of emails that bounce instead of reaching inboxes. There are two types of bounces: hard bounces (permanent delivery failures) and soft bounces (temporary delivery failures).

Bulk Email

Bulk email is sending a single email to many recipients (usually more than 25.) Bulk email works well for newsletters and promotions. Sending too many emails, sending them without permission, or pushing irrelevant content could be flagged as spam. Bulk email may also be referred to as an e-blast.

Bulletproof Buttons

Bulletproof buttons are link buttons in email content that are coded to ensure that they work consistently across all email clients and devices. These buttons display correctly and help connect readers to links. Bulletproof buttons are typically created using HTML and inline CSS to ensure maximum compatibility.

Buyer Persona

A detailed profile of an ideal target customer. It's a semi-fictional representation of your target customer based on data and research. Buyer personas guide marketing strategy by helping marketers understand who the customer is and what they want.

Call to Action (CTA)

A CTA urges readers towards a desired activity, such as buying a product or contacting the sender. It usually takes the form of a prominently placed prompt or button in an email. Effective CTAs use action words to drive clicks and conversions.

CAN-SPAM Act

The CAN-SPAM Act is a U.S. law that sets the rules for commercial email and gives recipients the right to have a business stop emailing them. Violating the CAN-SPAM Act can result in hefty fines. Guidelines adhere to general best practices, and following them can help improve trust in your brand.

Click-to-Open Rate

Click-to-open rate, or clicks per open, is a metric that measures the percentage of people who opened your email and clicked a link.

Clickthrough Rate (CTR)

CTR is the percentage of all email recipients who click on one or more links in an email. It's a popular metric to measure the success of an email campaign.

Cold Email

Cold emails are emails sent to potential leads who have had no previous contact or relationship with the sender. They are used to initiate sales conversations from the ground up. However, if the sender doesn't have a valid reason for reaching out, these emails can be seen as spam.

Content Delivery Network (CDN)

Content delivery networks (CDNs) are networks of connected servers that host files and images. They distribute email content quickly for better global delivery.

For example, if your email recipients are located in different countries, the CDN will find the closest server to deliver your content. This improves email load times and deliverability by reducing the load on your primary server.

Conversion Rate

This is the percentage of email recipients who take the desired action, such as clicking a link or making a purchase. Marketers measure different types of conversions depending on their goals. Tracking these conversions helps assess the overall return on investment (ROI) of an email campaign.

Cost per Thousand (CPM)

Advertising rates for email ads, such as sponsorships or placements, are often based on CPM, or cost per mille. In this pricing model, advertisers pay a fixed price for every 1,000 impressions, meaning they pay for every 1,000 emails delivered. This helps advertisers understand the cost of reaching a large audience through email campaigns.

Customer Data Platform (CDP)

A customer data platform (CDP) is a marketing technology that creates unified customer profiles by aggregating data from various sources such as CRM databases, website analytics, and email platforms. CDPs compile a single view of each customer based on their interactions across different channels.

Customer Relationship Management (CRM)

Customer relationship management (CRM) refers to the strategies, processes, and tools used to manage and analyze customer interactions and data throughout the customer lifecycle. More specifically, CRM software is the platform that manages these ongoing customer relations. A CRM system plays a crucial role in email marketing by helping businesses manage, organize, and optimize their interactions with customers and leads.

Dark Mode

Dark mode is an email design that features dark backgrounds to enhance reading comfort at night. This mode reduces blue light to provide a less disruptive user experience. Most modern email marketing platforms now offer some support for optimizing email for dark mode. This makes emails look sharp and easy to read in any lighting condition.

Dedicated IP

A dedicated IP is an exclusive IP address used solely by your business to send email messages. Unlike shared IPs, which are used by multiple senders, a dedicated IP allows you to build a unique sender reputation without conflicts from other users. Maintaining a dedicated IP's reputation requires adhering to proper email practices and good sending behavior.

Delivery Rate

Email delivery rate is the percentage of total emails sent that successfully arrive in subscribers' inboxes, rather than being bounced or rejected by the server. A high delivery rate maximizes the impact of your email campaigns.

Deployment

Deployment refers to the process of launching a pre-designed email campaign. Deployments transfer templates into active messages and may include automatic scheduling, coding, and testing.

DomainKeys Identified Mail (DKIM)

DomainKeys Identified Mail (DKIM) tags emails to validate senders. It uses cryptographic signatures to verify that an email message was sent from an authorized mail server and was not altered in transit. This prevents spammers from impersonating a legitimate domain.

Domain-Based Message Authentication, Reporting, and Conformance (DMARC)

DMARC is an email authentication protocol that builds upon SPF and DKIM to provide additional protection against email spoofing and phishing attacks. It allows domain owners to specify how email receivers should handle messages that fail authentication checks.

DocType

The doctype declaration is an instruction at the beginning of an HTML email that tells the email client which version of HTML (or plain text) is being used. Setting proper DocTypes prevents glitches across various devices and clients.

Double Opt-in

Double opt-in is the practice of requiring subscribers to confirm sign-ups by taking action on the inital email sent to them, or "opting in." This typically involves opening the email and clicking a link. Subscribers who fail to take this second step will not be added to the sender's mailing list and will receive no further communication. Using double opt-in proves that your list is made up of engaged, high-quality subscribers. In turn, that can improve your deliverability.

Dynamic Content

Dynamic content is email content that changes for each recipient based on their data, preferences, or behavior. Using dynamic content can help you create more personalized email experiences for your subscribers.

Dynamic content is often seen in ecommerce marketing. Different segments of a list will get a very similar email with slightly different messaging. For example, a clothing sale announcement might show male subscribers imagery of men's clothes while female subscribers see images of women's clothing.

E-Blast

An e-blast refers to sending a single email campaign to a whole subscriber list at once. E-blasts are often used for announcements and need to strike a balance between being informative and not coming across as spammy. This is a synonym of bulk email.

Email Automation

Email automation uses pre-set systems to trigger emails automatically, which eliminates the need for constant oversight. This approach allows marketers to send timely, relevant messages while saving valuable time and effort. (If you want to do a deep dive into email automation, check out our guide to email marketing automation strategy.)

Email Body

The email body is the main content area of an email message, typically located below the subject line and header. It contains the primary message and any supporting images, links, or calls to action.

Email Campaign

An email campaign is a coordinated series of related emails with shared themes and goals. Campaigns are typically sent to a specific audience to achieve a particular goal, such as promoting a product, nurturing leads, or driving event registrations.

Email Client

The email software or app used to receive and read messages. Popular clients include Gmail, Outlook, Yahoo, and more.

Email Editor

An email editor refers to functionality within email marketing software that’s used to design email layouts, insert content, and format text. These tools offer capabilities such as drag-and-drop interfaces, pre-designed templates, and custom HTML options. With an email editor, users can create visually appealing and effective email campaigns.

Email Filter

Filters are used by email clients to automatically sort incoming emails. These filters operate based on a set of rules that sort, mark, or remove emails according to specified criteria, such as the sender, subject line, or content. Filters are commonly used to block spam and prioritize important messages for a more organized and efficient inbox.

Email Framework

An email framework is a pre-designed structure or template for creating email campaigns. A well-designed framework provides a consistent layout, design elements, and best practices to ensure your emails are on-brand and effective.

Email Harvesting

Email harvesting involves collecting email addresses without consent for unauthorized spamming. The email addresses may be found on websites, online forums, or other public sources. This practice violates anti-spam laws.

Email Preview

Email preview is a functionality in email marketing software that allows you to see how your emails will appear in different contexts and email clients. This step is essential for testing and troubleshooting to ensure your message looks consistent and professional across all platforms.

Email Sponsorships

Email sponsorships are a type of paid email advertising where a brand pays to have their content or offer featured in another organization's email newsletter or campaign. This approach can effectively reach a new, targeted audience and drive traffic or conversions.

For senders with a large and well-targeted audience, email sponsorships provide an excellent opportunity to generate additional revenue.

Email Weight

Email weight refers to the total file size of an email, including all text, images, and HTML code. Larger email sizes can negatively impact load times and deliverability. Ideally, marketers should optimize emails and keep them as lightweight as possible.

Engagement Rate

Engagement rate measures interactions like opens, clicks, shares, and more. Depending on the chosen metrics, it gives you a holistic view of how well content resonates with subscribers. Engagement rate is assessed in different ways in email marketing, but usually involves looking at open rate, clickthrough rate, or click-to-open rate.

Fallback Text

Fallback text is a plain text version of your email that displays if the main HTML fails to load. Including fallback text ensures that your key message and call-to-action remain accessible to all recipients, even if they can't see the full design of your email. This guarantees that the essential content is always delivered, regardless of technical issues.

False Positive

A false positive occurs when a legitimate email is incorrectly flagged as spam by an email client's spam filter. Various factors can cause false positives, such as the use of certain trigger words, excessive images, or poor sender reputation.

Gray Mail

Gray mail refers to email messages that lie between legitimate emails and spam. These are often emails that recipients have subscribed to but no longer find valuable or engage with. Filters may hold gray mail in separate folders until approved, such as the "Promotions" tab in Gmail. This helps manage clutter while allowing users to review and approve emails they still want to receive.

Ghost Table

Ghost tables are invisible HTML elements used to structure the layout of an email before applying the final styling. They help format the positioning and spacing of content elements for a consistent and organized appearance across different email clients.

Hard Bounce

A hard bounce is a permanent email delivery failure caused by an invalid, closed, or non-existent email address. Hard bounces indicate unreachable recipients and can negatively impact the sender's reputation and deliverability.

Honeypot

In the context of email marketing, a honeypot is a technique used to identify and prevent spam sign-ups on email opt-in forms. A honeypot field is typically an invisible form field that humans cannot fill out, but spam bots can. When a spam bot fills out the honeypot field, the form submission is identified as spam and rejected.

House List

House list is the main subscriber list a business grows from its own customers. It's built over time through organic and legitimate opt-ins, such as website sign-ups, lead magnets, or in-person events. A house list is typically the most valuable email asset, as it contains subscribers who have directly expressed interest in a brand.

HTML Email

An HTML email is formatted using HTML and inline CSS. These emails use HTML code for visual formatting. HTML enables images, fonts, colors, and layouts. HTML email stands in contrast to plain text email, which only includes text.

Image Blocking

Image blocking is a default setting in some email clients that prevents images in an email from loading automatically. When images are blocked, recipients will see empty placeholders or alt text instead of the actual pictures.

Internet Message Access Protocol (IMAP)

Internet Message Access Protocol (IMAP) is the system managing interactions between email servers and clients. It allows users to access their email from multiple devices and synchronizes the email messages across all devices. Understanding how IMAP works can help troubleshoot email delivery and accessibility issues.

Inbox Placement Rate (IPR)

Inbox placement rate (IPR) measures the percentage of emails that successfully bypass spam filters and reach recipients' primary inboxes. A high IPR ensures better connectivity with recipients. Factors affecting IPR include sender reputation, email authentication, content quality, and subscriber engagement.

Inbox Service Provider (ISP)

An inbox service provider (ISP) is a third-party company that manages email deliveries for clients. ISPs optimize the routing of emails to navigate through various ISP filters.

Interactive Email

Interactive emails contain elements that allow recipients to engage directly within the email. These elements can include surveys, calculators, quizzes, and more.

IP Warming

IP warming refers to the practice of safely establishing new IP addresses. This is done by gradually increasing the volume of emails sent from a new or previously unused IP address. This process helps to establish a positive sending reputation for the new IP address, and prevents getting blocklisted upon sending out your first email campaign.

Landing Page

In email marketing, a landing page is a standalone web page that a user is directed to after clicking a link in an email. Landing pages convert clicks into actions with compelling offers.

Lead

A lead is a potential customer identified for further sales nurturing. In email marketing, leads are often generated through opt-in forms, lead magnets, or other sign-up incentives. Strong email leads are crucial for driving future revenue.

Lead Nurturing

Lead nurturing involves ongoing communication with potential customers to guide them toward making a purchase. The goal is to educate leads about your product or service and move them through the sales funnel, ultimately converting them into customers.

Lifecycle Email Marketing

Lifecycle email marketing involves strategically timing emails based on customer stages and behaviors. This approach ensures that relevant messages are sent at the right time, such as welcome emails for new subscribers, abandonment emails for shoppers who leave items in their carts, and re-engagement emails for inactive subscribers.

List Building

List building is the process of collecting more email subscribers. Solid list-building powers future engagement by attracting the proper recipients. Website sign-up forms, lead magnets, and social media campaigns are valid list-building methods.

List Churn

List churn refers to losing subscribers due to bounced addresses or unsubscriptions. High list churn can indicate issues with email content, frequency, or targeting. It may also suggest that it's time for a list cleanup.

List Fatigue

List fatigue occurs when subscribers become disengaged or uninterested in your email content due to receiving too many emails, irrelevant content, or a lack of value. List fatigue can lead to increased unsubscribes, spam complaints, and decreased engagement rates.

List Growth

List growth refers to the rate at which your email subscriber list increases over time. You can improve it by expanding an email list and adding new opt-in subscribers over time.

List Hygiene

Monitoring list quality by removing invalid emails and inactive subscribers is called list hygiene. The goal is to follow best practices to maintain a clean, accurate, and engaged email subscriber list.

List Segmentation

List segmentation means splitting an email list into groups with shared traits. These traits can pertain to shared characteristics, such as demographics, interests, purchase history, or engagement levels. Segmentation enables marketers to send more relevant content to each "segment" of subscribers.

Mail Delivery Agent (MDA)

A mail delivery agent (MDA) is responsible for delivering emails into inboxes after receiving them from servers. The process starts with mail submission agents (MSA) submitting outgoing emails. MDAs then work in conjunction with mail transfer agents (MTA) to route and deliver these emails to the recipient’s mail user agent (MUA), which is the email client used to read and compose messages, such as Gmail, Outlook, and Apple Mail.

Mail Merge

Creating personalized messages by combining templates with data files. For example, the placeholder [name] can be replaced with the actual names of subscribers in a mailing list gathered from a data file. Merges help marketers address each recipient individually. Most modern email marketing software includes this functionality.

Mail Submission Agent

The software sending outbound emails to recipients' servers for delivery. MSAs are responsible for initial email processing, including authentication and initial spam filtering.

Mail Transfer Agent

A mail transfer agent (MTA) is the server coordinating email transmission between different systems using the Simple Mail Transfer Protocol (SMTP). MTAs route messages to final destinations.

Marketing Automation Platform

Marketing automation platforms perform repetitive marketing tasks without constant oversight. Automation handles workflows like emails. They can also extend to social media and lead management duties. These platforms allow you to create complex email workflows, segment your audience, and track the performance of your campaigns.

Merge Tag

Placeholders in templates for personal data to populate. Tags merge individual details into customized content. The data comes from a separate source, like a data file or form submission.

Multipurpose Internet Mail Extension (MIME)

The standard format for attaching files and formatting emails. MIME enables rich multimedia email experiences and is supported by most modern email clients.

Modular Email Design

Modular email design refers to using simple, reusable content blocks for faster editing and email creation. Typically, there are different modules for solving particular needs, such as creating a footer, adding social media links, adding content, and more. Modular email design simplifies the design process and allows non-designers to create professional emails themselves.

MX Record

A DNS registry identifies servers that handle emails for specific domains. MX records are used to route email messages to the appropriate server for delivery.

No-Reply Address

Unique email addresses that only send automated responses. You'll often see them used as the sender address for automated or transactional emails, such as order confirmations or password reset emails. As the name suggests, human readers cannot reply to them. They are often formatted as noreply@domainname.com.

Nurture Sequence

A series of timed emails guiding subscribers toward a purchase or particular action. Sequences build relationships in a logical progression, usually based on website behavior, such as clicking a link from an email to a product page.

Onboarding Emails

Onboarding emails are a series of automated emails sent to new customers or subscribers to help them get started with a product or service. These emails often include welcome messages, tutorials, tips, and resources designed to help users get the most value from their experience.

Open Rate

The percentage of recipients opening an email. It's calculated by dividing the number of unique opens by the number of emails delivered. Higher open rates signal engaging subject lines. They may also signal that the subscriber trusts and values content from the sender.

Opt-in

Opt in is the process through which a user explicitly agrees to receive email communications from a sender. Opt-in permissions are typically obtained through sign-up forms, checkboxes, or other affirmative actions. Double opt-in requires confirming consent to ensure willingness.

Opt-out

Opt out is the opposite of opt in. Here, a user requests to be removed from an email list or stop receiving email communications from a sender. Sometimes, they may alter their sharing preferences to receive fewer communications.

Personalization

Personalization refers to custom-tailoring emails for individual recipients by name, location, preferences, etc. Personalization can help increase engagement, build stronger relationships, and drive more conversions.

Personally Identifiable Information

Personally identifiable information refers to private customer data like addresses, ages, and browsing history. This data can be used to identify, contact, or locate an individual. As such, it must be protected at all costs to maintain customer trust and comply with data privacy regulations.

Plain Text Email

Plain text email refers to messages that contain only text, without any formatting, images, or HTML elements. Plain text emails are helpful in reaching recipients who prefer simple, no-frills email communications or whose email clients do not support HTML.

Post Office Protocol (POP)

Post Office Protocol (POP) is an email retrieval protocol that allows email clients to download email messages from a mail server and store them locally on the user's device. Unlike IMAP, POP does not keep emails synchronized across multiple devices.

Postmaster

The postmaster is an internal email address (e.g. postmaster@example.com) that manages email servers and infrastructure. Postmasters are responsible for email deliverability and inbox placement for their domains, monitoring email traffic for spam, viruses, and abuse issues. They serve as a general contact point for other mail administrators to report email-related problems or ask questions. Contacting postmasters can provide valuable feedback if your emails are having deliverability issues.

Preference Center

A preference center is a dashboard that allows subscribers to manage email subscription preferences themselves. They may change things like email frequency, content categories, or communication channels. Preference centers give subscribers control over their email experience. By providing additional options - such as to unsubscribe from some but not all messaging - they can also reduce unsubscribes.

Preheader Text

Short text previewing email content, visible on inbox list views. Preheader text provides additional context and can entice recipients to open the email. Compelling preheader text complements the subject line and provides a compelling reason to engage with the email content.

Preview Pane

A preview pane is a feature in some email clients that allows users to view a portion of an email's content without opening the message. Some recipients don't want to open a message unless they know what's inside, so optimizing email design and content for preview panes makes them more likely to do so.

Progressive Profiling

Progressive profiling refers to the process of gradually gathering more subscriber data over time. It can be done through a series of very short forms or surveys. By not having to ask for all the information up front, progressive profiles avoid overwhelming subscribers.

Promotional Email

Marketing messages that primarily advertise products, services, or offers is called promotional email. This category may include discounts, limited-time offers, or other incentives to encourage recipients to take a desired action. Promotional content could educate and entertain readers as well.

Quarantine

Quarantine is the process of isolating questionable emails on an email service provider's servers before delivery to intended recipients. Emails may be quarantined if detected as potential spam or containing viruses or malicious content. Quarantining helps protect email subscribers from unwanted content and prevents legitimate emails from being permanently blocked without review.

Email marketers should be aware that their campaigns could end up in quarantine if their emails are flagged as suspicious, which can negatively impact deliverability. To avoid this, it's important that marketers understand why emails get quarantined. They can also follow email marketing best practices, such as domain authentication, maintaining a clean email list, and monitoring your sender reputation. Finally, some third-party tools like Litmus and Email on Acid can help you see how your email is likely to perform in terms of deliverability.

Read or Open Length

Read or open length is a metric that measures how long a recipient keeps an email open or engages with its content. Do they open it just to remove it from their inbox, or do they spend time reading and interacting with the content? Longer durations signify greater interest and attention.

Re-Engagement Campaign

The process of winning back inactive email subscribers with fresh content. Re-engagement restarts stalled relationships. These campaigns typically include special offers, personalized content, or requests for feedback to encourage recipients to interact with your emails again.

Rental List

A rental list is an email list temporarily acquired from a third-party provider for a specific email campaign. Rented lists allow marketers to expand and reach new audiences. Unfortunately, they often have lower engagement rates and higher spam complaints than organically grown lists.

Reply-to Address

The reply-to address is where email replies from subscribers are directed. This feature helps organize responses, especially for large teams. Setting a monitored and responsive reply-to address encourages two-way communication with your subscribers.

Segmentation

Segmentation involves grouping subscribers by shared attributes. This allows senders to personalize emails based on interests and characteristics, which can lead to improved engagement and more effective communication.

Sender Policy Framework (SPF)

Sender policy framework (SPF) is an email authentication protocol that helps prevent email spoofing by verifying that the sender's IP address is authorized to send emails on behalf of the domain. SPF records are published in the domain's DNS settings and are checked by receiving mail servers to validate the sender's identity.

Sender Reputation

Sender reputation is a measure of a sender's trustworthiness and credibility in the eyes of email providers and spam filters. Email service providers look at things like bounce rates, email engagement, and domain/IP reputation to assess whether a sender is likely to be reputable.

Sender Score

A sender score is a metric used by email clients to assess a sender’s reliability and integrity based on their past email habits. It’s a lot like a credit score, only rather than reflecting the likelihood that a person will pay their debts, it reflects how likely a sender is to send spam. A good sender score enhances email deliverability and makes sure that more of your emails reach recipients' inboxes.

Shared IP

Shared IP is when multiple senders share the same IP address, with all data being sent from the same server. Shared IPs cost less but provide less control. Likewise, the actions of other senders on the shared IP can affect the deliverability and reputation of all users.

Signature File

A signature file, or email signature, is a block of text, images, or HTML automatically added to the end of an email message. It serves as a personalized closing and contact section to build familiarity and provide essential contact information.

Single Opt-in

Single opt-in refers to adding people to email lists without double confirming consent. With single opt-in, a user is added to an email list immediately after submitting their email address through a sign-up form. Single opt-ins increase the risk of sending to uninterested or partly interested parties.

Soft Bounce

A soft bounce is a temporary failed email, as opposed to a hard bounce, which is permanent. It usually occurs when a recipient's email server is unavailable, the mailbox is full, or the message is too large. Soft bounces may still reach recipients later, as they will be retried for delivery over time.

Spam

Spam refers to unwanted, unsolicited emails. Spam wastes the inbox space of recipients for commercial gain or nefarious purposes. Email marketers must follow best practices and comply with anti-spam regulations to avoid having their messages classified as spam. Originally, the term spam was known to be short for “sales promotional advertising mail” or “simultaneously posted advertising message.”

SpamAssassin

A highly accurate, open-source spam detection system used by system administrators and email clients. SpamAssassin blocks or flags unwanted emails automatically. It uses a combination of techniques, such as text analysis, Bayesian filtering, and blacklists.

SpamCop

SpamCop is an external spam reporting service that allows users to report spam messages and helps email providers identify and blocklist spam sources. When a user reports a message as spam through SpamCop, the service analyzes the message and adds the sender's information to its database, which email providers then use to filter spam.

Spam Trap

A spam trap is a dummy email address used by internet service providers (ISPs) to catch spammers. There are two main types of spam traps: pristine traps, which are created solely to catch spam, and recycled traps, which are old, expired email addresses repurposed as spam traps. These emails are then placed where only spambots or unethical marketers would find them.

Sending emails to these addresses can severely damage your sender reputation. This can be avoided by maintaining best practices when it comes to attaining email addresses. Marketers should also clean their lists regularly.

Sender Policy Framework (SPF)

Sender policy framework (SPF) is an authentication system to prevent address spoofing, or sending email with a forged “from” address. It allows domain owners to specify which IP addresses are authorized to send emails on behalf of their domain. SPF records are published in a domain's DNS settings and are checked by receiving mail servers to verify the legitimacy of incoming email messages.

Spoofing

Email spoofing is the practice of sending emails with a forged sender (“from”) address, making it appear as though the message originated from someone or somewhere other than the actual source. Spoofing is often used in phishing attacks and spam campaigns. The goal is to trick recipients into believing the message is from a trusted sender.

Subscriber

In email marketing, this refers to a person who willingly opts in to receive emails. Subscribers are the foundation of an email list and are typically acquired through sign-up forms, lead magnets, or other opt-in incentives.

Template

An email template is a pre-designed layout that can be used as a starting point for creating email campaigns. It's a great tool for maintaining consistent branding, saving time, and simplifying the email creation process.

Throttling

Throttling is the practice of limiting the rate at which emails are sent from a particular IP address or domain. Email providers and ISPs may throttle email traffic to prevent overloading their servers and to protect against potential spamming activity. Senders can also self-throttle their email campaigns to safeguard their sender reputation and avoid triggering spam filters.

Tracking Pixel

A tracking pixel, also known as a beacon or web bug, is a tiny image file used to report email opens and locations. When a recipient opens an email containing a tracking pixel, the image is downloaded from a remote server, allowing the sender to record the open event and gather other data.

Trigger Email

Trigger emails are messages sent automatically when pre-set conditions occur. Examples of trigger emails include welcome emails, abandoned cart reminders, and post-purchase follow-ups. They are highly relevant and timely, making them an effective way to engage and convert subscribers.

Unique Opens

Unique opens refers to how many people opened an email, regardless of how many times they did so. This metric is in contrast to the total number of opens, which could include multiple opens by the same person. Unique opens are a valid way to measure reach.

Unsolicited Commercial Email (UCE)

Unsolicited commercial email (UCE) is another term for spam, referring to commercial email messages sent without the recipient's consent. Sending UCE is generally prohibited by anti-spam laws and can result in penalties, fines, and damage to the sender's reputation.

Whitelist

A list of approved email sources that bypass filters. Whitelists guarantee that messages get through. Subscribers can add senders to their personal whitelists, while senders can also apply to be added to global whitelists maintained by email providers and anti-spam organizations.