Email is one of the oldest digital marketing channels — and it’s still one of the most effective. While social media algorithms shift and paid ad budgets fluctuate, email continues to deliver a reliable return on investment.
In fact, many studies show that for every $1 spent on email marketing, businesses can see an average return of $36–$40.
“One of my favorite parts about email marketing is its intimacy,” explains Rob Litterst, head of strategy and operations for HubSpot’s Newsletter Network. “Access to someone’s inbox is sacred, and for a person to welcome you in, there’s already a certain level of trust that you just can’t achieve with other platforms”
Yet email marketing isn’t as simple as “write it, send it, and wait for clicks.”
Behind every great campaign is a mix of strategy, measurement, and continuous improvement. Consider this guide a refresher course in essential terms, metrics, and an explanation of how email marketing has evolved in the last five years.
What Is Email Marketing?
Email marketing, in a nutshell, is a simple and direct form of digital marketing that uses email to communicate with customers and prospects.
It is a way for businesses to send emails to people who have signed up (otherwise – you are sending spam and your brand never wants to be associated with that!), with the goal of promoting products, sharing updates, and building relationships.
These targeted messages work because email gives your business direct access to an audience without competing against a crowded newsfeed or paid ad auction. Your message lands in someone’s inbox — a personal, daily-use space — where you have the chance to grab attention, build trust, and encourage action.
Who Benefits from Email Marketing?
Email marketing isn’t just for e-commerce brands pushing online sales. It’s a versatile channel that benefits:
- B2B companies: Nurturing prospects with whitepapers, case studies, and webinars.
- Service businesses: Sending appointment reminders, seasonal promotions, or educational newsletters.
- Nonprofits: Connecting with donors, promoting fundraising events, and sharing impact stories.
- Local businesses: Announcing events, sales, or community involvement.
- E-commerce retailers: Driving cart recovery, cross-selling products, and rewarding loyal customers.
No matter the industry, if you have an audience that uses email (and who doesn’t? Even Gen Z uses email, but you might need a cheat sheet to understand the emojis, slang and abbreviations!), you can benefit from this channel.
Key Terms Every Marketer Should Know
Here’s a glossary of must-know email marketing terms, refreshed for 2025:
- Open Rate: The percentage of recipients who opened your email. (Less reliable today due to Apple Mail Privacy Protection, but still a directional metric.)
- Click-Through Rate (CTR): The percentage of recipients who clicked at least one link in your email. A strong indicator of engagement.
- Click-to-Open Rate (CTOR): The percentage of unique clicks divided by unique opens. Helps measure the effectiveness of your content once the email is opened.
- Conversion Rate: The percentage of recipients who completed a desired action after clicking (purchase, form fill, sign-up).
- Bounce Rate: Emails that couldn’t be delivered. “Soft bounces” are temporary (like a full inbox), while “hard bounces” are permanent (invalid address).
- Unsubscribe Rate: The percentage of recipients who opt out of your list.
- Spam Complaint Rate: How often recipients mark your email as spam.
- List Segmentation: Dividing your list into smaller groups (by behavior, demographics, or interest) for more targeted messages.
- Personalization: Tailoring content to the recipient (using their name, purchase history, or behavior).
- Automation: Trigger-based emails (such as welcome series, birthday offers or abandoned cart reminders) that are AI generated.
- Deliverability: The ability of your emails to actually reach inboxes instead of getting flagged as spam.
- Inbox Placement Rate: A newer metric used by sophisticated senders that tracks how often your emails land in the main inbox (vs. promotions, updates, or spam).
- Engagement Rate: A broader measure of how recipients interact with your emails over time (clicks, forwards, replies).
- Revenue per Email (RPE): Especially for e-commerce, the amount of revenue generated per email sent.
Why These Metrics Matter
Understanding these metrics is more than just reporting. They provide a roadmap to improve future campaigns:
- Low open rate? Test subject lines, sender names, and send times.
- Low CTR? Refine your copy, improve CTA buttons, or test visuals.
- High unsubscribe rate? Reevaluate your frequency or whether you’re delivering value.
- High bounce rate? Clean your list regularly to remove invalid addresses.
The right data points help you focus less on vanity numbers and more on actions that move the needle.
Email Marketing Has Evolved in Last 5 Years
Email marketing has evolved since 2020. Several key changes have shaped the industry over the past five years:
Personalization and Segmentation
- Before 2020, mass email blasts with limited targeting were common. Since then, businesses have increasingly shifted to sophisticated segmentation and personalized messaging, driven by consumer demand for relevance and stronger privacy regulations.
- Personalization now goes far beyond using first names— it leverages behavioral data, AI, and dynamic content for individualized experiences.
AI and Automation
- The use of AI in email marketing has grown dramatically, enabling smarter content creation, optimization, preview testing, and segmentation. In 2025, most marketers use AI as part of their workflow— but blending it with human editing is essential for audience engagement.
Interactivity and Mobile-First Design
- Interactive elements such as polls, surveys, carousels, and AMP-powered dynamic content have become common, fostering deeper engagement within emails.
- With the mobile majority, email design now starts with mobile-first approaches rather than simple mobile optimization to ensure high performance on small screens.
Privacy and Data Protection
- Enhanced privacy laws and compliance requirements (like GDPR and similar local statutes) now force marketers to ensure data security and consent, influencing how email lists are built and maintained.
- Privacy-centric, first-party data strategies are now key to ongoing email success.
Authenticity and Value-Driven Content
- The pandemic accelerated a shift toward value-driven, authentic communication rather than hard selling. Customers expect genuine, helpful content tailored to their needs, with plain-text and human-centric approaches gaining traction.
These documented trends show that email marketing has become more targeted, automated, interactive, privacy-focused, and customer-centric since 2020.
Why Email Still Works
In an era of TikTok, Instagram, and AI-driven ads, email might feel “old school.” But its reliability and ROI prove otherwise:
- It’s direct and personal.
- It’s cost-effective compared to paid ads.
- It builds long-term relationships instead of one-time impressions.
- It integrates seamlessly with other channels (social retargeting, content marketing, sales outreach).
In other words: email may be one of the oldest digital channels, but it’s also one of the most future-proof.
Email marketing in 2025 is both familiar and new. The fundamentals remain the same — deliver value, measure performance, and keep improving. But the tools, terms, and expectations have evolved.
If your business hasn’t revisited its email strategy in a while, now’s the time to refresh. A clear understanding of key terms and metrics can transform your campaigns from “just another email” into a meaningful driver of leads, sales, and customer loyalty.
Contact us today to start building email campaigns — including email newsletters filled with great content — that work.
