Email Glossary
Clear definitions of the email, deliverability, and marketing terms that matter.
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- Authentication ProtocolA set of technical rules and standards that verify the identity of an email sender and confirm that messages haven't been tampered with during transmission. Common protocols include SPF, DKIM, and DMARC, which work together to protect both senders and recipients.
- Authentication WrapperAn authentication wrapper is a security layer that encapsulates email authentication records (SPF, DKIM, DMARC) to protect against spoofing and unauthorized use of a sender's domain. It verifies that incoming mail genuinely originates from the claimed sender before delivery.
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- CAN-SPAM ComplianceAdherence to the U.S. CAN-SPAM Act, a federal law that sets mandatory rules for commercial email marketing, including requirements for clear identification, opt-out mechanisms, and accurate header information. Non-compliance can result in fines up to $43,792 per violation.
- Click-Through RateClick-through rate (CTR) is the percentage of email recipients who click on one or more links within an email message. It is calculated by dividing the total number of clicks by the total number of emails delivered, then multiplying by 100.
- Complaint RateThe percentage of emails marked as spam or reported as unwanted by recipients, calculated as complaints divided by total emails delivered. A key indicator of sender reputation and list quality.
- Conversion FunnelA visual model that tracks how subscribers progress through a series of stages—from awareness to action—such as landing on a page, opening an email, clicking a link, and completing a purchase. It helps identify where prospects drop off and which touchpoints are most effective at moving people toward a goal.
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- DeliverabilityDeliverability is the ability of a marketing email to reach a recipient's inbox without being filtered, blocked, or rejected by email service providers. It measures how successfully your messages arrive at their intended destination rather than bouncing or landing in spam folders.
- Drip CampaignA drip campaign is a series of automated emails sent to subscribers over a set period of time based on specific triggers or schedules. It delivers targeted content gradually to nurture leads, build relationships, and guide prospects through the customer journey.
- Dynamic Content BlockA segment of email content that automatically changes based on recipient attributes, behavior, or preferences, allowing a single email template to deliver personalized messages to different audiences. Dynamic content blocks adjust in real time without requiring separate email sends.
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- Email PersonalizationEmail personalization is the practice of tailoring message content, subject lines, and send times to individual recipients based on their data, behavior, and preferences. It goes beyond addressing someone by name to dynamically inserting relevant information that speaks directly to each subscriber.
- Engagement MetricsEngagement metrics are quantifiable measurements that track how recipients interact with your email campaigns, including opens, clicks, replies, and forwards. They reveal whether your content resonates with your audience and drive decisions about campaign optimization.
- Engagement ScoringA system that assigns numerical values to subscriber behaviors to measure and predict their level of interest in email communications. It helps identify which contacts are most likely to convert, remain loyal, or churn.
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- List DecayList decay is the natural decline in email list quality and engagement over time as subscribers become inactive, change email addresses, or lose interest. It occurs even with a well-maintained list and directly impacts deliverability, open rates, and overall campaign performance.
- List HygieneList hygiene is the practice of regularly cleaning and maintaining your email subscriber list by removing invalid, inactive, or unengaged addresses to improve deliverability and campaign performance. A well-maintained list reduces bounce rates, spam complaints, and protects your sender reputation.
- List SegmentationList segmentation is the practice of dividing your email subscriber base into smaller, targeted groups based on shared characteristics, behaviors, or interests. This allows you to send more relevant, personalized messages to each segment instead of broadcasting identical content to your entire list.
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- Reactivation CampaignA targeted email campaign designed to re-engage inactive subscribers who have not interacted with your emails or brand for a defined period. Reactivation campaigns aim to win back lapsed customers, reduce list decay, and determine whether to remove unresponsive contacts.
- Return Path ConfigurationReturn Path (also called bounce address or envelope sender) is the email address designated to receive delivery failure notifications and bounce messages. Proper configuration ensures bounce handling, feedback loop participation, and authentication alignment.
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- Seed TestingSeed testing is the practice of sending email campaigns to a list of known, controlled email addresses (seeds) before delivery to your main subscriber list to identify potential deliverability and rendering issues. This allows marketers to preview how their message will appear across different email clients and spam filters before it reaches real recipients.
- Sender ReputationSender reputation is a score or assessment assigned to your email sending domain and IP address by mailbox providers, based on historical email behavior and engagement metrics. It directly influences whether your emails reach the inbox, spam folder, or are rejected entirely.
- Send Time OptimizationSend Time Optimization (STO) is a technique that automatically determines and schedules email sends at the time each individual recipient is most likely to open and engage with a message. It uses historical engagement data and behavioral patterns to maximize open rates and click-through rates.
- SMTP RelayA mail server or third-party service that accepts outgoing emails from your application or system and forwards them to the recipient's mail server on your behalf. SMTP relays simplify email infrastructure by handling authentication, routing, and delivery logistics.
- Spam FilterA spam filter is an automated system that identifies and blocks unsolicited or malicious emails before they reach a recipient's inbox. These filters use machine learning, rule-based algorithms, and reputation databases to distinguish legitimate messages from spam, phishing attempts, and other unwanted content.
- Suppression ListA suppression list is a database of email addresses that should not receive future campaign communications due to previous unsubscribes, complaints, bounces, or other business rules. Maintaining an accurate suppression list is essential for protecting sender reputation and ensuring compliance with email regulations.