Key Metrics & Terms
Understand essential email marketing metrics to measure success and improve your campaigns with Brew
Email Marketing Metrics Overview
This page explains what each email metric means and defines essential terms, so you can better analyze your performance and ask smarter questions.
The basics—sends, opens, and clicks—are right there in your email dashboards. But when you’re ready to dig deeper into things like bounce rates or spam complaints, that’s where Brew’s Ask AI feature comes in handy.
What’s on This Page
Navigate to the section that interests you most:
Core Engagement Metrics
- Open Rate - How compelling are your subject lines, preview text, and brand?
- Click Rate - How engaging is your content and CTAs?
- Conversion Rate - Are you driving business results?
Deliverability Metrics
- Bounce Rate - How clean is your contact list?
- Unsubscribe Rate - Is your content valuable to recipients?
- Complaint Rate - Is your content relevant?
Strategic Insights
- Open Tracking & Deliverability - Understanding tracking limitations
- Focus on Business Impact - Moving beyond vanity metrics
Reference
- Email Marketing Terms - Complete glossary with 25+ essential terms
Core Engagement Metrics
Open Rate
Open rate measures the percentage of delivered emails that recipients opened.
How open rates are tracked
How open rates are tracked
When you send an email through Brew, here’s exactly how opens are measured:
- Tracking Pixel Insertion: A 1×1 pixel transparent GIF image is automatically embedded in each email you send. This invisible pixel contains a unique identifier linked to both the specific email and the recipient.
- Email Delivery: Your email is delivered to the recipient’s inbox with this tracking pixel included.
- Image Loading: When a recipient opens your email and their email client loads images, it requests this pixel from Brew’s servers.
- Open Registration: This server request registers as an “open” in Brew’s analytics system, recording who opened the email and when it happened.
- Data Processing: Brew consolidates this data to calculate your open rate, filtering out duplicate opens from the same user to provide unique open metrics.
Why open rate matters
Why open rate matters
Open rate is a key indicator of email engagement and the effectiveness of your subject lines, preview text, and sender reputation. It shows whether recipients find your emails worth opening based on these initial impressions and their previous experience with your brand.
Benchmarks
Benchmarks
Average open rates vary by industry, but generally:
- 15-25% is considered average
- Above 25% is good
- Above 35% is excellent
Limitations to consider
Limitations to consider
Open rates have become increasingly unreliable due to privacy protections and technical limitations:
- Apple Mail Privacy Protection (iOS 15+): Automatically pre-loads tracking pixels, causing emails to show as “opened” instantly whether actually read or not
- Corporate email security: Many companies use firewalls that cache or block tracking pixels
- Email client defaults: Some clients block image loading by default, preventing open detection entirely
Focus more heavily on click-through rates and conversions as more reliable engagement indicators.
Use Brew’s Ask AI feature to ask questions about your open rate performance, such as: “What subject line patterns have led to the highest open rates for my newsletter?”
Click Rate
Click rate (also known as Click-Through Rate or CTR) is the percentage of delivered emails that resulted in recipients clicking a link within the email.
Click rate reflects how engaging and relevant your email content is, and how compelling your calls-to-action are. Strong CTAs with clear value propositions, appealing design, and strategic placement significantly impact your click rates.
How clicks are tracked
How clicks are tracked
Brew tracks clicks through a process called link rewriting:
- Link Modification: When you create an email, Brew automatically rewrites all links to route through our tracking servers before redirecting to the final destination.
- Unique Identifiers: Each rewritten link contains parameters that identify both the email campaign and the specific recipient.
- Click Registration: When a recipient clicks any link, they first connect to Brew’s tracking system, which records the click event along with relevant data (which link, which recipient, timestamp).
- Instant Redirect: After registering the click, the recipient is immediately redirected to the intended destination URL. This happens so quickly that recipients don’t notice any delay.
- Reporting: Brew aggregates this click data to calculate metrics like click rate and identifies which specific links received the most engagement.
Why CTR matters
Why CTR matters
Clicks represent the next level of engagement beyond opens. They indicate that your message was compelling enough for recipients to take action.
Across industries, a 2–5% CTR is common for email campaigns, with around 2.3% being the average.
Use Brew’s Ask AI feature to explore your click rate data with questions like: “Which types of links get the most clicks in my emails?” or “What content sections drive the most engagement?”
Open Tracking and Deliverability
How tracking affects deliverability
How tracking affects deliverability
While open tracking provides valuable insights, it can impact where your emails land in recipients’ inboxes:
- Promotional signals: Tracking pixels are commonly used by marketers and spammers, so inbox providers may flag emails with tracking as promotional content
- Spam detection: Some email providers use the presence of tracking pixels as one factor in spam filtering algorithms
- Transactional email impact: For transactional emails (receipts, confirmations, password resets), tracking pixels can reduce inbox placement since these should appear more “system-generated”
Links and opens in transactional emails are never tracked in order to improve deliverability. This helps ensure these critical emails reach recipients’ inboxes without being filtered as promotional content.
Conversion Rate
Conversion rate measures the percentage of recipients who completed your desired action after receiving your email.
Unlike opens and clicks, conversions are tracked in your own analytics platforms (like Google Analytics), not within Brew. Brew helps you drive conversions through optimized emails, but you’ll need to set up external tracking to measure these business outcomes.
Why conversion rate matters
Why conversion rate matters
Conversion rate is crucial because it measures the business impact of your email campaigns. While opens and clicks are important engagement metrics, conversions represent actual business outcomes.
Tracking conversions
Tracking conversions
To track conversions, you’ll need to:
- Define the specific action that constitutes a conversion for each campaign
- Add UTM parameters to your email links
- Connect your analytics platform (like Google Analytics) to track these actions
- Set up goals or events in your analytics platform to measure completion
Deliverability Metrics
Bounce Rate
Bounce rate measures the percentage of emails that could not be delivered.
Bounce rate primarily reflects the quality and hygiene of your contact list. High bounce rates typically indicate outdated or incorrectly collected email addresses rather than issues with your email content or sending practices.
Types of Bounces
Hard Bounces
Permanent failures due to invalid addresses or blocked domains
Soft Bounces
Temporary issues like full mailboxes or server problems
How bounces are tracked
How bounces are tracked
Brew tracks bounces through automated feedback from email servers:
- Delivery Attempt: When your email is sent, it goes through multiple servers before reaching its destination.
- Bounce Detection: If a receiving mail server cannot deliver the message, it sends back an automated response (an SMTP error) with a specific reason code.
- Classification: Brew’s system automatically categorizes these bounce responses into hard bounces (permanent failures) or soft bounces (temporary issues) based on the error codes and message.
- Recording: The bounce is logged in your campaign metrics along with the specific reason for the failure.
- Automated Handling: For hard bounces, Brew automatically suppresses the email address to prevent future sending attempts, protecting your sender reputation.
If your bounce rate exceeds 2% (20 bounces per 1,000 emails sent), Brew may temporarily suspend your account to protect your domain reputation and the deliverability of the platform. High bounce rates severely damage sender reputation and can lead to deliverability issues for all users. Regular audience hygiene practices can help maintain healthy bounce rates.
Unsubscribe Rate
Unsubscribe rate measures the percentage of recipients who opted out of future emails.
Why unsubscribe rate matters
Why unsubscribe rate matters
Unsubscribe rate indicates whether your audience finds your content valuable and relevant to their needs. High unsubscribe rates suggest that recipients aren’t getting the value they expected from your emails, or that your content isn’t resonating with their interests and needs.
Benchmarks
Benchmarks
Most email experts consider an unsubscribe rate below 0.5% to be normal.
How unsubscribes are tracked
How unsubscribes are tracked
Brew tracks unsubscribes through an intuitive preference management system:
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Unsubscribe Link: Every email sent through Brew includes a legally-required unsubscribe link, typically in the footer. This link contains a unique identifier for the recipient.
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Preference Center: When a recipient clicks this link, they’re taken to your branded Preference Center rather than being immediately unsubscribed. Here they can see all your subscription groups with descriptions.
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Granular Control: Instead of a single “unsubscribe from everything” option, recipients can use toggle switches to choose which specific content types they want to continue receiving. This reduces total unsubscribes by letting contacts opt out of only the content they don’t want.
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Immediate Processing: When a recipient updates their preferences, Brew instantly records these changes and updates their status in your audience.
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List Suppression: The system automatically ensures this contact will no longer receive emails from the unsubscribed groups, while still allowing them to receive content from groups they remain subscribed to.
Brew automatically handles the entire unsubscribe process for you. Unsubscribed contacts are skipped when sending campaigns and automations, but they will still receive transactional emails (like password resets and order confirmations) since these contain essential information. This behavior ensures compliance with CAN-SPAM regulations, which distinguish between marketing and transactional communications.
Learn about the Preference Center
Customize how subscribers manage their email preferences with your branding
Learn about Subscription Groups
Create content categories that give subscribers more control over what they receive
Complaint Rate
The complaint rate is the percentage of delivered emails that recipients marked as “Spam” or “Junk”.
How complaints are tracked
How complaints are tracked
Complaints are tracked through a standardized system called Feedback Loops (FBLs):
- Recipient Action: A recipient clicks the “Mark as Spam” or “Report Spam” button in their email client.
- ESP Notification: The receiving email service provider (like Gmail, Yahoo, or Outlook) captures this action and sends a standardized report through a Feedback Loop.
- Complaint Processing: Brew receives these FBL reports and associates them with the specific email campaign and recipient.
- Automatic Suppression: The complainant’s email address is automatically added to a suppression list to prevent any future emails from being sent to them.
- Metric Calculation: Brew aggregates these complaints to calculate your complaint rate and provides alerts if rates approach concerning thresholds.
If your complaint rate exceeds 0.08% (less than 1 complaint per 1,000 emails sent), Brew may temporarily suspend your account to protect your sender reputation and the deliverability of the platform. This threshold aligns with industry standards from major email service providers like Gmail and Yahoo, which recommend keeping complaint rates below 0.1%. Ensuring your content is relevant and that you’re sending to engaged contacts can help maintain low complaint rates.
Additional deliverability insights: Monitor your sender reputation regularly to ensure optimal deliverability. While Brew tracks essential metrics automatically, you can gain deeper insights into how different email providers view your sending reputation by using specialized reputation monitoring tools.
Boost your deliverability with self-engagement: Send a test email to yourself, open it, and reply to it. This simple action signals to email providers that your content is valuable and engaging, which can positively impact your sender reputation and improve inbox placement.
Focus on Business Impact
While engagement metrics like opens and clicks provide valuable insights, the most important question is whether your emails drive meaningful business results.
Move beyond vanity metrics
Move beyond vanity metrics
- Revenue attribution: Track how much revenue can be attributed to specific email campaigns
- Goal completion: Monitor actions that matter to your business (free trial signups, demo bookings, feature adoption)
- Customer lifecycle: Measure how email marketing influences customer retention, upgrades, or referrals
- Time to action: Track how quickly recipients take desired actions after receiving emails
Practical approaches
Practical approaches
- UTM parameters: Add tracking codes to email links to monitor website behavior and conversions in your analytics platform
- Event tracking: Set up tracking for specific actions like downloads, form submissions, or account activations
- Revenue tracking: Connect email campaigns to sales data to understand ROI
- Cohort analysis: Compare the behavior of engaged email subscribers vs. non-subscribers
Start with one business metric: Pick the most important business outcome for your emails (signups, purchases, feature adoption) and track that consistently before adding complexity.
Email Marketing Terms
Essential terms to understand when analyzing your email performance with Brew:
Above the Fold
Above the Fold
The portion of your email that recipients can see without scrolling. Critical for placing your most important content and calls-to-action where they’ll be immediately visible.
Automations
Automations
Multi-step email flows that are automatically triggered by specific contact actions, behaviors, or timeframes. Used for onboarding new customers, driving product adoption, nurturing leads, retaining customers, upselling customers, and winning back inactive users. In Brew, you describe your automation goal and the AI builds the entire flow with optimal timing and branching logic. Learn more about Automations.
Bounce Rate
Bounce Rate
The percentage of emails that couldn’t be delivered to recipients. Includes both hard bounces (permanent failures) and soft bounces (temporary issues like full inboxes). Brew automatically handles bounce management to protect your sender reputation.
Call to Action (CTA)
Call to Action (CTA)
A button or link in your email designed to prompt a specific action from recipients, such as “Download Now” or “Get Started.” Essential for driving conversions. Learn how Brew automatically optimizes CTAs in Campaigns.
Campaigns
Campaigns
One-time emails sent to multiple recipients simultaneously. Perfect for announcements, newsletters, promotions, events, and other standalone communications. With Brew, you describe your campaign goal and the AI generates, personalizes, and optimizes your email in seconds. Learn how to create Campaigns.
CAN-SPAM Act
CAN-SPAM Act
U.S. federal law that sets rules for commercial email, including requirements for unsubscribe links, sender identification, and truthful subject lines. Compliance is mandatory for U.S. senders. Brew automatically ensures compliance in all marketing emails. Learn more about CAN-SPAM.
Click-Through Rate (CTR)
Click-Through Rate (CTR)
The percentage of email recipients who clicked on one or more links in your email. A key indicator of content engagement and email effectiveness. Use Brew’s AI analytics to understand what drives higher CTR.
Contact Properties
Contact Properties
Data fields associated with each contact in your audience, such as firstName, lastName, company, or custom fields. Used for personalization through merge tags and audience segmentation in Brew. Learn how to add and manage Contact Properties.
Conversion Rate
Conversion Rate
The percentage of email recipients who completed your desired action (purchase, signup, download) after clicking through from your email. The ultimate measure of email success. Track conversions using UTM parameters and analytics platforms.
Deliverability
Deliverability
Your ability to successfully deliver emails to recipients’ inboxes rather than spam folders. Affected by sender reputation, content, and authentication. Brew optimizes deliverability through proper domain verification.
Pro tip: Send test emails to yourself, open them, and reply to them. This simple self-engagement signals to email providers that your content is valuable, which can positively impact your sender reputation and deliverability.
DKIM
DKIM
DomainKeys Identified Mail - an email authentication method that verifies your emails haven’t been tampered with during transit. Helps improve deliverability. Set up DKIM through domain verification.
DMARC
DMARC
Domain-based Message Authentication, Reporting & Conformance - an email security protocol that prevents domain spoofing and improves deliverability when properly configured. Configure DMARC as part of domain verification.
Double Opt-In
Double Opt-In
A two-step subscription process where users must confirm their email address by clicking a link after initially signing up. Ensures higher quality subscriber lists and better audience hygiene.
Email Service Provider (ESP)
Email Service Provider (ESP)
A platform like Brew that provides email marketing and delivery services, including analytics, automation, and deliverability optimization. Brew serves as your complete system of record for email marketing.
Hard Bounce
Hard Bounce
An email that permanently fails to deliver due to invalid email addresses, non-existent domains, or blocked recipients. These contacts are automatically suppressed by Brew to protect your sender reputation.
Common causes of hard bounces include:
- Email address contains a typo (e.g., [email protected])
- Email address doesn’t exist (perhaps the person left the company)
- Email server has permanently blocked delivery
- Domain no longer exists
When an email hard bounces, Brew automatically adds it to your suppression list, preventing future sending attempts to protect your deliverability. You can see the specific bounce reason in your campaign reports by hovering over the bounce status.
Tips to reduce hard bounces:
- Use double opt-in for all new subscribers
- Regularly clean your email list with audience hygiene practices
- Check for common typos in email domains (like gmail.com, outlook.com)
List Hygiene
List Hygiene
The practice of maintaining a clean email list by removing inactive subscribers, invalid addresses, and unengaged contacts to improve deliverability and metrics. Learn about audience hygiene best practices.
List Segmentation
List Segmentation
Dividing your email list into smaller, targeted groups based on demographics, behavior, or preferences to send more relevant and effective campaigns. In Brew, create targeted audiences and subscription groups.
Merge Tags
Merge Tags
Open Rate
Open Rate
The percentage of delivered emails that recipients opened. While useful for trends, modern privacy protections make this metric less reliable than clicks and conversions. Use Brew’s analytics to focus on actionable metrics.
Personalization
Personalization
Customizing email content for individual recipients using data like names, locations, or past behavior. Typically increases engagement and conversion rates. Brew automatically personalizes emails using contact properties and merge tags.
Preference Center
Preference Center
A branded page where subscribers can manage their email preferences and choose which subscription groups they want to receive emails from, rather than unsubscribing completely. Customize your Preference Center in Brew.
Preview Text
Preview Text
The snippet of text that appears after the subject line in most email clients. Often called “preheader text,” it provides additional context to encourage opens. Brew’s AI automatically optimizes preview text for each email.
Sender Reputation
Sender Reputation
A score assigned by internet service providers based on your sending history, bounce rates, complaint rates, and engagement. Critical for inbox placement. Maintain good reputation through proper domain verification and audience hygiene.
Soft Bounce
Soft Bounce
An email that temporarily fails to deliver due to issues like full inboxes or server problems. These addresses aren’t permanently suppressed and may receive future emails. Brew automatically manages soft bounces and retry logic.
SPF Record
SPF Record
Sender Policy Framework - a DNS record that specifies which servers are authorized to send email on behalf of your domain. Essential for email authentication. Set up SPF records through domain verification.
Split Testing (A/B Testing)
Split Testing (A/B Testing)
Testing different versions of an email element (subject lines, content, CTAs) with different segments of your audience to determine what performs better.
Subscription Groups
Subscription Groups
Content categories that allow subscribers to choose what types of emails they want to receive from you. In Brew, these replace traditional “lists” and provide more granular control over subscriber preferences, reducing total unsubscribes. Learn how to create and manage Subscription Groups.
Suppression List
Suppression List
A list of email addresses that are blocked from receiving your emails, typically including unsubscribes, hard bounces, and complaintants. Brew automatically manages suppression lists to ensure compliance and protect deliverability.
Why Brew maintains a suppression list:
- Protects your sender reputation: Continuing to send to invalid addresses or complainants damages your domain reputation
- Improves deliverability: Email providers track how often you attempt to send to invalid addresses
- Ensures compliance: Automatically prevents sending to people who have unsubscribed
Common reasons email addresses are suppressed:
- Hard bounces: The email address doesn’t exist, contains a typo, or the server has permanently blocked delivery
- Complaints: Recipients who have marked your emails as spam
- Unsubscribes: People who have opted out of your communications
Brew automatically handles suppression list management, so you don’t need to manually remove these addresses. You can view suppressed addresses in your Audience section and see the specific reason they were suppressed.
Transactional Email
Transactional Email
Automated emails triggered by specific user actions containing essential information, such as password resets, order confirmations, or account notifications. These emails typically have 4-5x higher open rates than marketing emails and are sent regardless of subscription status. Learn about Transactional Emails.
Trigger
Trigger
The starting condition that determines when and how contacts enter an automated email sequence. Brew supports four trigger types: Contact added, A dded to subscription group, Contact updated, and Event received. Learn about Triggers and Events.
Unsubscribe Rate
Unsubscribe Rate
The percentage of recipients who opt out of your email list after receiving a campaign. Monitored to gauge content relevance and list health. Reduce unsubscribes by using subscription groups and your preference center.
UTM Parameters
UTM Parameters
Tags added to email links that help track traffic sources and campaign performance in analytics platforms like Google Analytics. Use UTM parameters to measure the business impact of your email campaigns beyond basic open and click rate metrics.
Complaint Rate
Complaint Rate
The percentage of recipients who mark your email as spam. High complaint rates severely damage sender reputation and deliverability. Maintain low complaint rates through relevant content and proper subscription groups management.
Subject Line
Subject Line
The title of your email that appears in recipients’ inboxes. One of the most important factors influencing whether your email gets opened. Brew’s AI automatically generates optimized subject lines for all campaigns and automations.
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Click “Open in ChatGPT” at the top right of any page to analyze documentation with ChatGPT or Claude for deeper insights.
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