Imagine two CRM managers launching a promotional campaign on the same day. They work in similar industries, target comparable audiences and offer equally compelling value. One sees their emails landing in the inbox, open rates climbing and sales following. The other notices a drop in performance: unsubscribes rising, spam reports multiplying and some campaigns not even reaching the inbox anymore. Yet their offer is comparable.
The difference does not come down to a single factor. It relies on three dimensions that, together, determine whether an email is seen, understood and acted on: content, design and relevancy.
These three topics are often treated separately. In reality, they all influence the same thing: how your readers react. Every open, every click, every deletion or spam report becomes a signal that mailbox providers use to decide whether your next emails deserve a place in the inbox (and those signals are the foundation of your deliverability).
What's less obvious is that every choice you make contributes to these signals: targeting, subject line, content, tone, design, sending frequency and even how easy it is to unsubscribe.
This guide shows you how to make these levers work together to build emails that perform durably 🚀
Understanding the email performance chain
Before diving into content, let's lay the groundwork. An email does not produce a conversion directly. It goes through a series of interdependent steps:
Getting delivered → getting opened → getting clicked → driving an action.
Each step conditions the next and a deliverability issue cannot be fixed with great copywriting, nor can weak content be saved by great design. All three need to work together.
Understanding deliverability: why every choice matters
Deliverability refers to your emails' ability to actually reach your subscribers' inboxes, as opposed to landing in spam or being blocked. It is often seen as a purely technical topic but in reality it is also tied to the quality of your emails and the attention your readers give them.
Mailbox providers rely on a variety of reputation, complaint and engagement signals, which vary by provider. Positive behaviours (opens, clicks, forwards) reinforce your sender reputation. Negative ones (deletions without reading, spam complaints, or consistent silence) can degrade it over time.
User feedback, especially spam complaints, can directly affect future inbox placement.
💡 Useful and engaging emails send positive signals → better inbox placement → better business performance. This is a virtuous circle and email content quality is what drives it.
Deliverability is not just a technical topic. Every email you send influences your sender reputation.
Relevancy: reaching the right person at the right time
Content and design determine how your email looks and reads. But before any of that matters, a prior question shapes everything: is this email relevant to the person receiving it?
Relevancy covers four dimensions: who you send to, how personalised the message is, how often you send and how easy it is to opt out. Get these right and your emails earn attention. Get them wrong and even the best content won't save you.
Segmentation: start with "who?"
Before starting to build your email template, one question comes first: who is this email for?
Sending the same message to your entire base dilutes its impact. The more relevant your message is to its recipient, the more likely it is to be opened, clicked and trusted.
Thinking about segmentation also means knowing who to stop sending to. Continuing to reach out to inactive contacts degrades your overall engagement and, with it, your deliverability. Learn more: List hygiene & recipients management.
Now that you know who you are writing to, a new question arises: what will that person see first? That is where personalisation comes in.
Personalisation: going beyond the first name
Segmentation defines who you are sending to. Personalisation adapts what each reader sees.
Personalisation exists on a spectrum: from no personalisation at all, to adding a first name, to truly contextual messages built on what your user actually did. The third level is where the real impact happens.
Personalisation is often thought of as adding a first name to the subject line. That is a good start but you can go much further with two types of data:
User data: purchase history, favourite category, last action, loyalty level...
Catalogue data: products, prices, images, recommendations...
Combined, they enable truly contextual messages:
✅ "It's been a while Nina! New sneakers just dropped and they match your last purchase"
❌ "Discover our latest arrivals"
✅ "Justine ! Barcelona from €79, just saying 👀"
❌ "Our best deals this week"
The difference isn't just stylistic. The first message shows the reader that you know them: their habits, their preferences, the right moment to reach out. The second could have been sent to anyone. One builds trust, the other blends into the noise.
Our recommendations:
Prioritise contextual personalisation (based on user actions) over cosmetic personalisation.
Do not overdo it: too much information in a single message hurts clarity.
A personalised email does not just recognise the reader, it speaks to them.
Sending frequency and marketing pressure: finding the right balance
The quality of your emails is not enough: sending frequency matters just as much:
Too few communications and your brand risks disappearing off the radar.
Too many and you expose your subscribers to a kind of fatigue that can lead to unsubscribes, spam reports and, over time, a drop in deliverability.
Frequency is not part of content, but it directly influences how your emails are perceived.
Finding the right cadence, setting up frequency capping, offering a preference centre and monitoring engagement signals are all levers for maintaining a lasting relationship with your subscribers.
This topic will soon be covered in detail in a dedicated article.
Unsubscribing: a strategy, not a constraint
Making it easy to unsubscribe protects your deliverability. A reader who no longer wants your emails has two options: unsubscribe or mark you as spam. A spam complaint can be significantly more damaging to your sender reputation, which is why it is better to:
Have a visible unsubscribe link (not just tiny text buried in the footer)
Offer a preference centre: fewer emails rather than none at all
Never make opting out unnecessarily difficult. Where processing relies on consent, GDPR requires withdrawing consent to be as easy as giving it.
For bulk senders, unsubscribe is not only a UX best practice. Gmail and Yahoo require specific List-Unsubscribe mechanisms. Batch automatically adds List-Unsubscribe headers (both one-click and mailto) to all marketing emails. The visible unsubscribe link in the email body remains your responsibility as a sender.
Learn more about common Footer & Unsubscribe Link Mistakes (and How to Fix Them)
A voluntary unsubscribe is worth far more than a passive contact quietly penalising you.
Content: earning the read
Once relevancy is established, the message itself takes over. Content determines whether your email gets opened, understood and acted on, from the very first word of the subject line to the final CTA.
Subject line and preheader: winning the Inbox battle
You know who you are writing to. You've thought about personalisation. Now you need to convince your reader to open your email because without an open, nothing else happens.
A good subject line does not try to be clever at all costs. It needs to be clear, credible and user-oriented. Before finalising yours, ask yourself: "Why should I open this email right now?"
The preheader plays a complementary role that's often underestimated. Left empty it defaults to the first line of the email body and this is a missed opportunity. Used well, it adds context, reinforces the promise and increases the desire to click.
Think of it as a strategic extension of the subject line, not a repetition.
Our recommendations:
Front-load the key information: mobile inboxes display less of the subject line, and truncation varies by device and email client. Stay under 40 characters or front-load the essential if you go longer and let the preheader carry what the subject line doesn't need to
Prefer clarity over creativity
Use concrete elements: limited time, benefit, action, number...
Avoid vague phrasing ("Our latest offers", "Discover our news")
Align subject line and actual content: a misleading promise creates disappointment and unsubscribes
Test multiple variants (A/B or A/B/C/D)
E-commerce (promotion) example:
✅ Subject line: "30% off sneakers, today only"
✅ Preheader: "Offer valid until midnight"
❌ Subject line: "Our latest offers"
❌ Preheader: "Discover our new arrivals"
Media (newsletter) examples:
✅ Subject line: "3 ideas to improve your emails starting today"
✅ Preheader: "A 3-minute read"
❌ Subject line: "Our weekly newsletter"
❌ Preheader: "The latest news"
A good subject line does not try to be clever. It gives a clear reason to open.
Writing to be understood in seconds
The email is open. Now everything happens very fast.
Readers typically scan marketing emails rather than reading every word. In a few seconds, they decide whether they understand the message, whether they're interested and whether they'll click.
That is where writing makes all the difference. Here are the 5 pillars of content that converts.
Make the message clear
The reader needs to understand immediately why they're receiving this email. Speak in user benefits, not product features, and state the topic in the very first sentence.
✅ "Your spring picks are here. 20% off until Sunday."
❌ "We are pleased to announce our new spring-summer collection..."
Focus on a single intention (where possible)
A high-performing email is centred on one main goal. Stacking CTAs risks splitting attention and dividing clicks, the reader does not know what to do, so they do nothing.
Five CTAs competing for attention (shop, browse, read, manage your account, refer a friend) and the reader ends up clicking none. One clear CTA, and the path is obvious.
Drive action
Content should naturally lead to action. The CTA in particular should use action language and express what the user gains, not what you are offering.
✅ "Claim my offer" / "See what's new"
❌ "Click here" / "Learn more"
Balance text and images
There is no universal text-to-image ratio. What matters is avoiding image-only emails and ensuring key information remains understandable when images don't load.
Why? Because images are disabled by default in some email clients: if your message relies solely on visuals, some of your readers will see nothing. It is also a matter of accessibility: an email that's readable without images remains understandable for all readers, including those using assistive tools.
Keep image file sizes in check too: heavy images slow load times and hurt the reading experience, especially on mobile.
Images should serve the content, not replace it.
Design for mobile
Most emails are read on mobile, often on the go or between tasks. Yet it is one of the most frequently overlooked aspects: many emails are designed on desktop and never tested on mobile before sending.
The result: text is too large, CTAs are not thumb-friendly, poorly cropped images.
The requirement is simple: your email needs to be understood instantly, whatever the screen. Short sentences, airy layout, thumb-friendly CTA. If the reader has to work to understand your message, they won't click.
Good content does not just inform. It triggers a decision.
Tone and brand voice: writing for someone
Content says what. Tone says how. It is often the tone that makes the difference between an email someone reads and one they close.
A generic message, even with a great offer, generates less engagement than one that feels written specifically for you. It is a question of trust: we stop on emails that recognise us.
✅ "We thought of you for this one."
❌ "Dear customers, we are pleased to inform you..."
A few principles for finding the right tone:
Address the reader directly ("you") : avoid "our customers" or "users"
Keep a human register, even on commercial topics : an email is not a catalogue
Adapt tone to context: a reactivation campaign is not written like a flash promo and a transactional email is not written like a newsletter
Stay consistent across emails : a consistent tone builds trust and brand recognition
Avoid internal jargon : your reader does not know your codes
A good tone goes unnoticed. It simply makes the reading feel natural and easy.
Design: making the action obvious
Content carries the message. Design makes it accessible. Its role is not to (simply) make the email look good, it is to guide the eye towards the action.
Making the message visible, readable and actionable
Here are the 3 pillars of an effective design:
Create a visual hierarchy
The first job of design is to establish a clear hierarchy: the reader needs to know where to look first, without having to search. This means:
Highlighting the key elements (headline, offer, CTA)
Creating reading levels (headings, subheadings, distinct blocks)
Avoiding dense layouts that bury the essentials
Make scanning easy
As we saw on the content side: your readers scan. Design needs to support this behaviour, not work against it. To do this:
Use short and airy blocks
Leave visual breathing room (whitespace)
Avoid long paragraphs
Put the action front and centre
Finally, design needs to make the CTA impossible to miss. This means:
Making the CTA visible without scrolling
Using strong visual contrast on the button
Removing any visual distractions around it
🎓 Design in Emails is covered in depth in a dedicated module on the Batch Academy, feel free to watch it to go further.
The click is not the end
An often-overlooked factor in email performance: what happens after the click.
An email can drive a lot of traffic without generating conversions, simply because the landing page is not aligned with its promise.
Common examples
Email 1 : "3 practical tips to improve your emails"
❌ Generic blog homepage
✅ The article itself directly
Email 2 : Warm, personalised email
❌ Cold, transactional landing page
✅ Page with an aligned tone that extends the relationship initiated in the email
To maximise impact, ensure a seamless continuity between the email and the destination page: same promise, same tone, same offer, same level of urgency.
The email prepares the user. The page finalises the action. Both need to form one coherent journey.
Test to improve
A/B testing is not just for subject lines. Everything can be tested: CTAs, structure, tone, send time.
A few rules:
Test one variable at a time
Set a hypothesis before launching: "I think a first-person CTA will generate more clicks"
Document results, each test informs the next
Testing is not a one-off, it is a mindset. The brands that improve fastest in email marketing are the ones that test continuously.
🎓 A/B test is covered in depth in a dedicated module on the Batch Academy, feel free to watch it to go further.
Pre-send checklist
Conclusion
A high-performing email is never the result of a single factor. It is the subtle balance between content, design and relevancy that builds lasting performance (and that's what makes it such a fascinating challenge to work on):
🎯 Relevancy determines whether your email deserves a place in the inbox
✍️ Content determines whether it is interesting and drives action
🎨 Design determines whether it is easy to understand
Of course, content quality cannot compensate for authentication or sending infrastructure issues, but get all three right, and you create the engagement signals that support healthy deliverability over time.
Every campaign is a new opportunity to send the right signals :
To mailbox providers which will decide your visibility
To your subscribers who will decide whether to open, click or forget you.
The best email strategy is the one your readers are waiting for. Everything else follows from that!
Justine Di Meo
Team Lead Onboarding & Care
Follow us
The CRM Newsletter
Subscribe to get the latest news in your inbox!
