
Email Marketing: what it is, how it works and how to do it
Learn how email marketing works, the main types, how to build your contact list, choose a tool, avoid spam and measure the results of every campaign.

What will we see in this post
Email marketing is a communication strategy that uses email to send messages to a list of contacts.
Within a digital marketing strategy, email can serve different purposes, such as:
- inform: announce news, a product update or a change in rules;
- build relationships: stay present between one purchase and the next, without asking for anything;
- distribute content: take what you publish to people who have already shown interest;
- nurture: prepare people who are not yet ready to buy;
- convert: present the offer and lead the reader to the purchase page;
- retain and recover: bring back people who abandoned their cart or stopped opening your emails.
Before starting email marketing campaigns, it is important to define the purpose of each message. The biggest mistake in an email marketing strategy is trying to fulfill all of these purposes in the same email.
In this guide, we separate one from the other, build your list from scratch, break an email down into its parts and look at what to measure after you hit send.
How does email marketing work?
Email marketing was born in May 1978, when Gary Thuerk, a marketing manager at Digital Equipment Corporation, sent a promotional message to 393 addresses on the ARPANET network, announcing a new line of computers.
In an interview with Computerworld, Thuerk said the campaign sold between 13 and 14 million dollars’ worth of machines, and at the same time generated the first recorded wave of complaints about unsolicited commercial emails.
That initial tension shaped the next steps of the strategy.
By the 1990s, when mass sending became routine, providers began filtering unsolicited messages, and the market ended up moving to the permission model that still applies today.
That is why an email marketing strategy must always start with the user explicitly authorizing the company to contact them.
After authorization, that email address goes into a segmented contact list, so messages are routed correctly based on interest, timing and the promise made to the user.
Sending is automated by market tools.
Finally, the email provider decides whether the message reaches the inbox or the spam folder, a part many people overlook.
In this flow, you control the first three steps, but the one who decides the final destination of the message is Gmail, Outlook or Yahoo, and their decision depends on the reputation of your sending domain.
How does consent separate email marketing from spam?
The difference between email marketing and spam is not in the content, but in the authorization. A well-written, useful email sent to someone who did not ask for it is still spam.
In Brazil, Law 13,709/2018, the LGPD, defines consent as a free, informed and unambiguous statement for a specific purpose. Article 8 adds two points that change how you build your form: generic authorizations are void, and consent can be revoked at any time through a free and easy procedure.
Translated to your operation: the person needs to know they will receive your emails, know what they will be about, and be able to leave the list without having to ask.
Email marketing, transactional email and newsletter: what is the difference?
The three terms are commonly used as synonyms, but they are not. The difference lies in the sending trigger and the need for authorization.
| Type | What it is | When it is sent | Needs opt-in? |
|---|---|---|---|
| Email marketing | Commercial or relationship message sent to a contact list | By scheduled campaign or automated flow | Yes |
| Transactional email | Confirmation of an action the user took: purchase, signup, password reset | Instantly, triggered by the action | No, it comes from the relationship with the customer |
| Newsletter | A format within email marketing, with fixed periodicity and a focus on content | At a set interval: weekly, biweekly, monthly | Yes |
In practice, a newsletter is a type of email marketing, not a separate category.
Advantages of email marketing
The main advantage of email marketing is control. The list is yours, reach does not depend on an algorithm and the cost per contact does not go up when competitors increase their media spend.
Predictable reach, with no algorithm deciding who sees it
On social media, the reach of a post is defined by an algorithm you do not control and that changes without notice. With email, the message is sent to every valid address on your list.
That does not mean everyone will open it. It means delivery depends on the quality of your list and the reputation of your domain, and you can work on both.
An audience you own
If a social network changes its rules, cuts your reach or suspends your account, the audience you built there stays locked in the platform. Your email list does not.
You export the contacts, switch tools and keep talking to the same people. That is why the list is often called an asset.
Low cost and measurable return
To start an email marketing strategy, you need a domain, a sending tool and someone to write. Almost every platform has a free tier for small lists, which lowers the barrier to entry.
The return is also measurable. You can calculate your ROI with a simple formula:
ROI = (revenue generated by the campaign minus campaign cost) divided by campaign cost, multiplied by 100.
Lead nurturing throughout the funnel
Not everyone who joins your list is ready to buy. Most are not. Email is the channel that lets you follow that person until they are ready.
This process is called lead nurturing: you send content that helps the person understand their problem before offering your solution.
In practice, each email in the sequence corresponds to a stage of the sales funnel. Someone who just joined receives discovery content. Someone who has already consumed three materials receives the offer.
This is how email fits into inbound marketing: attraction happens outside the inbox, but conversion and the purchase decision tend to happen inside it.
Personalization and behavior-based segmentation
Segmenting means splitting your list into smaller groups so each group receives a different message.
The criterion can be declared interest, what the person has already bought, how long since they opened an email or what they clicked in the last send. You can even rank contacts by engagement with lead scoring.
The practical rule: only create a segment if the message will change because of it. Otherwise, it is extra work with no return.
After-sales, repurchase and relationship
Selling again to someone who has already bought usually costs less than winning a new customer. Email is the natural channel for this, because the person already authorized contact when they bought.
This is where satisfaction surveys, product usage walkthroughs, new content alerts and complementary offers come in. All of that is after-sales, and none of it depends on ads.
Flexible format, no character limit
An email can be three lines or three pages, text only or image, with one button or none. There is no character limit or format imposed by the platform.
That freedom is both an advantage and a trap. Without a clear goal per email, the tendency is to pile everything into the same message and convert nothing.
Email marketing challenges
On the other hand, email marketing also has its limitations. The most important one: sending is not the same as delivering, and delivering is not the same as being read.
Deliverability is not guaranteed
Between hitting send and the message appearing in the inbox, there is a decision layer that is not yours. The provider evaluates your domain reputation, your complaint history and the technical authentication of the send.
If something there fails, the email goes to spam or is rejected without notice. It is the point that sinks the most campaigns from people who are just starting out.
The inbox is saturated
You are not competing for attention only with other businesses. You are competing with the bank, the school, social media and the newsletter the person signed up for two years ago and forgot about.
That is why the subject line and the sender name weigh more than the email content. If the message is not opened, the rest never even gets evaluated.
The open rate became an unstable number
The open rate stopped being a reliable metric in 2021, when Apple began preloading email images for people who turn on privacy protection in the Mail app.
The feature is not on by default, the person chooses it the first time they open the app, but adoption is high. Since opens are measured by a tracking pixel inside the image, the system records opens that never happened.
The Litmus State of Email report points out that automated bot activity has made the open rate unreliable, which has led the best-performing teams to look at revenue per email and list churn.
Do not throw the metric away, but treat it as a trend, not an absolute number. When making decisions, look at clicks and conversions.
An outdated list drags down campaign performance
A contact list loses validity on its own. People change email addresses, abandon old accounts and lose interest in the topic that brought them to you.
Sending to invalid addresses increases the bounce rate, and a high bounce rate hurts domain reputation. That is why a large, idle list performs worse than a small, active one.
The channel demands consistency and a calendar
Email marketing does not work in bursts. Someone who disappears for three months and comes back with an offer tends to collect unsubscribes and spam complaints, because the person no longer remembers authorizing the contact.
And consistency takes work.
Someone has to write, review and schedule the send every week or every month. That is a real operating cost, and it is worth factoring in before promising a frequency you will not be able to keep.
Data protection compliance is an obligation, not a choice
Collecting an email address is processing personal data. That puts your operation under the LGPD, with obligations to record consent, state the purpose and make unsubscribing easy.
And this is not bureaucracy reserved for large companies: it applies equally to someone with 200 contacts and someone with 200 thousand.
What are the types of email marketing?
The types of email marketing fall into three large groups: relationship, promotional and transactional.
- Relationship emails exist to keep the conversation alive without asking for anything. Newsletters, new content and satisfaction surveys belong here.
- Promotional emails present an offer and ask for a commercial action. Launches, discounts and cart recovery belong here.
- Transactional emails confirm something the person did: bought, signed up, requested a password reset. Technically they are not email marketing, but they are part of the same operation and tend to have the highest open rates on the list.
| Type | Goal | Sending trigger |
|---|---|---|
| Newsletter | Stay present and distribute content | Fixed calendar |
| Lead nurturing | Prepare the contact for the purchase | Entering an automated flow |
| Promotional and offer | Present an offer and lead to the purchase | Scheduled campaign |
| Welcome | Confirm the signup and take the first step | Joining the list |
| Seasonal and holiday | Take advantage of a relevant date | Calendar date or contact date |
| Cart abandonment | Recover an unfinished purchase | Abandoned cart |
| Inactive contact reactivation | Bring back those who stopped opening | Time without interaction |
| Invitation, launch and event | Drive attendance at an event or launch | Event date |
Newsletter
A newsletter is the fixed-periodicity email that delivers content, news and curation to people who subscribed. It is the simplest format to start with, because it does not depend on an automated flow or complex segmentation.
Its value is in repetition, not in each individual edition. Someone who receives your newsletter every Thursday starts to look forward to it.
Lead nurturing email
It is a sequence of emails that takes the person from not knowing to deciding. Each message answers a question and prepares the next one.
It works best when you map your audience’s real objections and write one email for each, instead of repeating the sales pitch in different formats.
Promotional and offer email
This is the email that presents the product, the price and the deadline. It needs one goal and one button only, because each additional option splits the click.
Watch the proportion. If every email you send is promotional, unsubscribes go up and domain reputation drops with them.
Welcome email
The welcome email is the first email a person receives after signing up, and it tends to be the best performer on the whole list, because it arrives at the moment of highest interest.
Use it to confirm what the person will receive and how often, and to deliver right away what was promised in the form.
Seasonal and holiday email
The contact’s birthday, Black Friday, Christmas, Mother’s Day: these are emails with a set date, which lets you schedule them in advance and reuse the structure every year.
The caution is relevance: a holiday that has nothing to do with your product becomes noise in the inbox.
Cart abandonment email
It is triggered when someone starts a purchase and does not finish it. It is the email marketing flow with the highest direct return, because it speaks to someone who has already shown purchase intent.
It usually works best as a short sequence: a quick reminder, a second email addressing the most common objection and, if it makes sense for your business, a special offer.
Inactive contact reactivation email
This is the email for people who have not opened anything in months. It serves two purposes: recovering those who are still interested and identifying those who no longer are, so you can clean the list.
Here, a direct question usually works better than an offer: ask whether the person wants to keep receiving your emails and what they would prefer to hear from you.
Invitation, launch and event email
It is the sequence that comes before a date: live class, cart opening, in-person event. It has a beginning, middle and end defined by the calendar.
The technical point of attention is volume. A launch sequence concentrates many sends into a few days, and that is exactly where deliverability problems show up.
How to do email marketing
Doing email marketing is a ten-step process, from defining the goal of your messages to the first send.
You do the first four once. The rest repeat with every campaign.
1. Define the campaign goal and who it is for
Before writing a single line, answer two questions: what do you want the person to do after reading and who is that person.
The goal needs to be a single, measurable action: click a link, reply to the email, download a material, complete a purchase. A generic goal like “strengthen the brand” cannot be measured or optimized.
About the audience: describe in one sentence who will receive it and where that person is in their journey. “People who downloaded the pricing material in the last 30 days and have not bought yet” is an audience. “My list” is not.
2. Choose the email marketing tool
Do not send email marketing from your personal email provider. Mass sending through a regular Gmail or Outlook account damages your sender reputation and usually ends in the account being blocked.
An email marketing tool takes care of what you cannot do by hand: authenticating the send, processing unsubscribes and recording metrics.
3. Authenticate your domain before the first send
Authenticating the domain means setting up three DNS records that prove you are who you say you are: SPF, DKIM and DMARC. Without them, the chance of landing in spam is high from the very first send.
The setup is done in the control panel of whoever hosts your domain, and the email marketing tool provides the exact values to enter.
Do it before the first send. Sender reputation is built with history, and a bad history takes much more work to fix than to avoid.
4. Make it easy to subscribe and unsubscribe
Joining your list and leaving it should take the same effort: one click. This seems counterintuitive for someone building a list, but it is what protects the health of the channel in the long run.
On the subscription side, the form should make it clear what the person will receive and how often, and ask for as few fields as possible. Each additional field lowers the completion rate.
On the unsubscribe side, the unsubscribe link must be visible in the footer of every email, work without requiring a login and process the exit immediately. No form with five questions before letting the person leave.
This is not just good manners.
Since February 2024, anyone sending large volumes to Gmail accounts must offer one-click unsubscribe and process the request within two days.
And there is a practical logic to it.
Someone who cannot find the exit button marks your email as spam, and a spam complaint weighs much more on your reputation than an unsubscribe.
5. Build and organize your contact list
With the email marketing tool set up and the capture form live, collection begins.
What matters here: never start with a purchased list or one imported from another context. A contact who did not authorize you complains about spam, and the first complaints are precisely the ones that hurt a new domain the most.
6. Segment the list by a criterion that changes the message
Segmenting means splitting the list into groups that will receive different content. The most useful criteria for beginners are four:
- Signup source: which material or page brought the person in. It indicates declared interest.
- Journey stage: already bought, never bought, bought a long time ago.
- Recent interaction: opened or clicked in the last 90 days, or not.
- Declared preference: what the person themselves said they want to receive.
Start with two. More than that, at the beginning, creates a production volume you will not be able to sustain.
7. Write the email and build the template
Here you define subject, sender, body and button. Each of these elements has its own rules.
An important recommendation for this process: write the body first and the subject last. A subject written before the text tends to promise something the email does not deliver, and a broken promise lowers the open rate of your next campaigns.
8. Define the frequency and build the sending calendar
Frequency is the decision that most influences unsubscribes. There is no universal number, but there is a principle: the frequency you can sustain with quality is better than the ideal frequency you cannot maintain.
Build a calendar at least four weeks ahead, marking the date, goal and segment of each send. This avoids two common problems: months of silence and three emails piling up in the same week.
State the frequency right on the signup form and stick to it. Someone who signed up expecting one email a week and receives one a day marks it as spam, and rightly so.
9. Automate the flows that run on their own
An automated flow is a sequence triggered by an action of the contact, without you pressing any button. Three flows cover most of the results for beginners:
- Welcome: triggered at signup, delivers what was promised and introduces you.
- Cart abandonment: triggered when the purchase is not completed.
- Post-purchase: triggered after the purchase, with usage guidance and a path to the next purchase.
Email automation works while you are not working, and that is great because it minimizes the chances of human error, such as forgetting to send or sending the wrong message.
10. Test the send before firing it to the whole list
Send the email to yourself and to two or three more addresses from different providers. Open it on your phone and on your computer.
Check four things: that all links work, that the images load, that the text remains readable with images blocked and that the email did not land directly in the promotions tab or in spam.
How to build your email list
An email list is built by offering something in exchange for the contact. Nobody fills out a form out of generosity: the person hands over their email because they want what is on the other side.
Offer a lead magnet worth the visitor’s email
A lead magnet is a free material you deliver in exchange for the signup. The formats that work best for people who work with content and digital products are:
- PDF material: a guide, ebook or handout about a specific problem.
- Ready-made template: a spreadsheet, checklist or script the person uses the same day.
- Recorded class or webinar: video content on a focused topic.
- Email mini-course: a sequence of messages that teaches something, which already delivers value and trains the habit of opening your emails.
- Simple tool: a calculator, simulator or diagnostic that returns a personalized result.
The selection criterion is just one: the lead magnet must solve a piece of the same problem your product solves. A misaligned one attracts people who will never buy and inflates your list with contacts who open nothing.
Where to place capture forms
The form needs to be where the person has already shown interest, not in just any corner of the site. The best-performing spots are the end of an article on your blog that the person has finished reading, a dedicated landing page for the lead magnet and the most visited content area of your site.
For a newsletter, a banner or a pop-up with the email field is enough, as long as the pop-up does not cover the content before the person has read anything.
It is also worth using your social media bio, your video descriptions and your personal email signature. These are spaces you already have and that cost nothing.
Single opt-in and double opt-in: when to use each?
With single opt-in, the person fills out the form and joins the list right away. With double opt-in, they receive a confirmation email and only join after clicking the link.
| Criterion | Single opt-in | Double opt-in |
|---|---|---|
| List size | Grows faster | Grows more slowly |
| Contact quality | Lower, includes typos and fake addresses | Higher, only those who confirmed get in |
| Bounce rate | Higher | Lower |
| Proof of consent | Form record | Form record plus the confirmation click |
| When to use | Small lists, low-friction lead magnets | When deliverability and proof of consent matter |
For anyone who sells digital products and depends on email to generate revenue, double opt-in usually pays off.
Which fields to ask for in the form (and which not to)
Ask for the email and, at most, the first name. Each extra field lowers the completion rate, and you do not yet have enough of a relationship to justify the question.
Phone number, job title and revenue can come later, in an email that asks directly or in a next-step form.
Why you should never buy an email list
Buying an email list is illegal in Brazil and technically counterproductive. Illegal because the LGPD requires free, informed and unambiguous consent from the data subject, and a list sold by a third party has none of that.
Counterproductive because the contacts do not recognize your sender and mark it as spam. Complaints concentrated on a new domain sink your reputation, and then even the emails to people who did authorize you stop arriving.
The same goes for importing contacts from another context: event attendees, a partner’s customers, followers who sent a message. Authorization is valid for a specific purpose, not for any future use.
How to clean your list and keep contacts valid
Cleaning means removing from your contact list the addresses that should no longer be there. Do it every three to six months, using three criteria:
- Addresses that hard bounce: nonexistent or deactivated email. Remove on the first permanent bounce.
- Contacts with no opens or clicks for more than six months: try to reactivate them with a specific send and, if there is no response, remove them.
- Addresses with an obvious typo: misspelled domains. Some can be fixed, the rest go.
Removing contacts hurts, we know. But it is what keeps your delivery rate high.
What are the elements of an email marketing message?
An email marketing message has nine elements, and each one solves a different problem on the path between the inbox and the click. When a campaign does not convert, the flaw usually lies in one of them, not in the whole email.
| Element | Function | Most common mistake |
|---|---|---|
| Sender name and address | Make the person recognize who is speaking | Using a generic address like noreply |
| Subject line | Get the open | Promising what the email does not deliver |
| Preheader | Complement the subject in the preview | Leaving it blank and showing the start of the code |
| Header | Visually confirm who the email is from | Taking up half the screen with a banner |
| Email body | Deliver the message and lead to the button | Putting several topics in the same email |
| Images and GIFs | Illustrate and give rhythm to the reading | Putting the main information inside the image |
| CTA | Turn reading into action | Using more than one action per email |
| Footer | Identify the sender and allow opting out | Hiding the unsubscribe link |
| Size and responsiveness | Ensure the email opens and displays in full | A file that is too heavy and a layout that breaks on mobile |
Sender name and address
The sender name is the inbox’s first filter, even before the subject. Use a name the person recognizes: your name, your brand name or both together.
Avoid addresses like “noreply” or “contact”. They signal automated communication and reduce the chance of a reply, and a reply is a positive signal for providers.
Subject line
The subject has one job: get the open without misleading. As a practical market rule, something between 30 and 50 characters tends to work well, because it fits entirely on a phone screen.
Stating the concrete benefit and being specific instead of generic help the open rate. It is worth looking at catchy title ideas and the responsible use of mental triggers.
Preheader, the preview text
The preheader is the snippet that appears next to or below the subject in the inbox, before the person opens the email. If you do not set it, the provider shows the beginning of the email, which often produces an “If you cannot see this message” in the preview.
Treat the preheader as a continuation of the subject, not a repetition. The subject says the what, the preheader says the why.
Header and visual identity
The header visually confirms who the email is from. A simple strip with your logo does the job.
Be careful with big banners. They push the content down and, if images do not load, the person opens the email and sees an empty rectangle.
Email body
The body structure that works in most cases: context in one sentence, what you are offering, why it matters to that person and the button.
For scannability, prefer paragraphs of up to three lines, with one idea per paragraph and bold only on what the person needs to see if they read just half.
In addition, limit yourself to one topic per email.
Images, GIFs and alt text
Most providers load images automatically today. Gmail has done so since 2013, through its own servers. But blocking still happens in two situations you do not control: when the provider considers the message suspicious and when the person disabled loading in their settings.
In other words: the email needs to make sense without the images.
Never put important information only inside the image: price, deadline and button stay in text, and always fill in the alt text of every image, which appears when it does not load and helps people who use a screen reader.
This also applies to GIFs in email, which some clients display only as a static frame.
CTA
The CTA is the button or link that takes the person to the action you defined in step 1. Use one per email, repeated at most twice in the same text.
The button text should say what happens after the click. “Download the guide” works better than “Click here”, because it removes doubt about the destination.
Footer
The footer needs to have the name and identification details of the sender, and a visible unsubscribe link, in a readable size.
It is tempting to hide the unsubscribe link in light gray and tiny type. Do not. Someone who cannot find the exit button clicks “mark as spam”, and that costs far more.
File size and responsiveness
Very heavy emails can be clipped by some providers, which hides exactly the end of the message, where the button is. Keep the file lean and compress the images.
Also, test the email on a small screen before sending. Mobile accounts for a good share of opens, in a proportion that varies by industry and by list.
Which email marketing tools should you use?
The best email marketing tool is the one that delivers your emails, automates the flows you need and connects with the place where the sale happens. Brand and popularity matter less than these three points.
What to evaluate before choosing a platform
- Deliverability and authentication: the platform must provide SPF, DKIM and DMARC records and let you use your own sending domain.
- Automation: can you create flows with triggers, waits and conditions, or can you only schedule sends on a fixed date?
- Checkout integration: can the tool tell who bought, who abandoned the cart and who canceled? Without that, you lose the flows with the highest return.
- Free tier limit: how many contacts and how many sends per month, and what gets locked when you go beyond that.
- Reports: delivery, open, click, bounce and unsubscribe at the very least. If it shows revenue per campaign, even better.
- Support in your language and billing in your currency: it seems like a detail until the day a launch send fails.
How far do free email marketing tools go?
Almost every platform has a free tier, and it is enough to get started.
The limit usually shows up in four places: number of contacts, number of sends per month, access to automation and the presence of the tool’s branding in the footer of your emails.
In practice, the free plan holds up well through the first few thousand contacts, or until the day you need an automated flow.
When is it worth moving to a paid plan?
Three signs indicate it is time to pay for an email marketing tool: you need an automated flow and the free plan does not offer it, your list passed the contact limit, or you need a revenue-per-campaign report to decide where to invest.
If your digital product is already sold on Hotmart, the all-in-one platform for creators, Hotmart Send operates inside the same environment as the checkout.
That solves the integration criterion with no extra setup: the tool already knows who bought, who abandoned the cart and who is an affiliate, and comes with ready-made templates and artificial intelligence support for writing your emails.
How much does email marketing cost?
You can start at no cost at all. The price of email marketing is defined by the size of the list and the sending volume, not by the size of the company.
| List size | Monthly cost range | What is usually included |
|---|---|---|
| Up to about 1,000 contacts | Generally free, with a limit that varies by platform | Scheduled sending, ready-made templates, basic reports. Limited or no automation |
| 1,000 to 10,000 contacts | Entry-level plans | Automation, segmentation, A/B testing and removal of the tool’s branding |
| 10,000 to 50,000 contacts | Mid-tier plans | Advanced automation, integrations, revenue reports |
| Over 50,000 contacts | Custom-quote plans | Dedicated IP, priority support, deliverability consulting |
Prices vary widely between platforms and change often, which is why the table works with ranges. Confirm the current number directly on the pricing page of the tool you choose.
Also watch out for three things that make the bill bigger and often go unnoticed: inactive contacts that keep being charged, extra sends outside the contracted package and features charged separately, such as automation or testing.
Which email marketing metrics should you track?
There are seven email marketing metrics that tell you whether a campaign worked, and each one answers a different question. Looking at only one of them leads to the wrong conclusion.
| Metric | Formula |
|---|---|
| Delivery rate | Emails delivered divided by emails sent, times 100 |
| Open rate | Unique opens divided by emails delivered, times 100 |
| Click-through rate (CTR) | Unique clicks divided by emails delivered, times 100 |
| Click-to-open rate (CTOR) | Unique clicks divided by unique opens, times 100 |
| Conversion rate | Conversions divided by emails delivered, times 100 |
| Unsubscribe rate | Unsubscribes divided by emails delivered, times 100 |
| ROI | Revenue minus cost, divided by cost, times 100 |
Delivery rate
It measures how many emails reached the destination server. It is the first metric to look at, because all the others depend on it.
A delivery rate below 95% usually points to one of two problems: a list with invalid addresses or an unauthenticated domain. The first is solved with list cleaning, the second with SPF, DKIM and DMARC.
Open rate
It measures how many people opened, based on a tracking pixel embedded in the message. It is the most cited metric and also the least reliable today.
Since 2021, Apple Mail’s privacy protection preloads images and records opens that never happened. Add to that security bots, which also open emails on their own.
Keep tracking it, but as a trend. If your open rate drops 15 points from one month to the next, that means something. If it stayed at 38% instead of 43%, it probably means nothing.
Click-through rate (CTR)
The click-through rate measures how many people clicked on any link out of the total emails delivered. It is more reliable than the open rate, because a click requires deliberate human action.
A low CTR with a high open rate indicates the subject is working and the content is not. In general the problem is the button: either it does not exist, or it is not clear, or it competes with other actions in the same email.
Click-to-open rate (CTOR)
It measures how many of those who opened clicked. It is the metric that evaluates the email content separately from the subject.
If the CTOR is good and the CTR is bad, the problem is the open, not the content. If the CTOR is bad, the problem is what is inside the email.
Conversion rate
It measures how many people completed the action you defined as the goal: purchase, signup, download. It is the only metric that speaks the same language as your business.
To measure it, you need tracking on the links, with parameters that identify the campaign. Without that, you know who clicked but not who bought because of the email.
Unsubscribe rate and spam complaint rate
An unsubscribe is someone who asked to leave. A spam complaint is someone who clicked “mark as spam”. Both measure dissatisfaction, but they weigh very differently.
A high unsubscribe rate is a sign of the wrong frequency or relevance. A spam complaint, on the other hand, directly affects your sender reputation, and Google asks bulk senders to keep that rate below 0.3%.
Email marketing ROI
ROI measures the financial return on what you invested in the channel. The cost of the tool, the time of whoever writes and any outsourced production go into the calculation.
How to make sure your email reaches the inbox
Deliverability is the ability of your emails to reach the inbox instead of the spam folder. It depends on three factors you control: domain authentication, list quality and complaint history.
It is the most technical part of email marketing and also the most treacherous: the problem only becomes visible after it has already turned into a bad reputation.
SPF, DKIM and DMARC explained without jargon
They are three records you add to your domain’s DNS. Together, they prove to the destination provider that the message really came from whoever claims to have sent it.
| Record | What it does |
|---|---|
| SPF | Lists which servers can send email on behalf of your domain |
| DKIM | Digitally signs the message, proving it was not altered along the way |
| DMARC | Tells the provider what to do when SPF or DKIM fail, and sends reports to you |
The setup is done only once, in your domain provider’s panel, with the values the email marketing tool hands you ready-made. It takes a few minutes and solves most delivery problems.
What did Gmail and Yahoo start requiring from bulk senders?
Since February 1, 2024, anyone sending more than 5,000 messages per day to Gmail accounts must meet a list of technical requirements. Yahoo adopted equivalent rules around the same time.
According to Google’s official guidelines, bulk senders must:
- Set up SPF and DKIM authentication for the sending domain.
- Set up DMARC for the sending domain, with a policy that can start as “none”.
- Offer one-click unsubscribe and process the request within two days. This specific requirement began to be enforced in June 2024, a few months after the others.
- Keep the reported spam rate below 0.3%.
- Use a TLS connection to transmit messages and maintain valid DNS records for the sending domains.
List cleaning and spam complaint rate
The 0.3% spam complaint limit is tighter than it seems. On a list of 10,000 contacts, that is 30 complaints. A single poorly targeted campaign can reach it.
Two practices keep that number down: removing inactive contacts from time to time and making the unsubscribe link easy to find.
What to do when the launch send is large
A launch sequence is the highest-risk deliverability scenario, because it concentrates high volume into a few days, often from a domain with little history.
If you have never sent high volume before, increase sending gradually in the weeks leading up to the launch, starting with the contacts who interact the most. This builds reputation before the peak.
During the launch, monitor delivery and complaints at every send, not just at the end of the campaign. If complaints go up, reduce the volume and cut the coldest segments before continuing.
Most common email marketing mistakes
The most frequent mistakes are not about writing, but about process. The table below links each mistake to the symptom it produces in the metrics and to the fix.
| Mistake | Symptom in the metrics | Fix |
|---|---|---|
| Sending everything to the whole list | High unsubscribes and low CTOR | Create at least two segments and adapt the message |
| Not personalizing anything | Open and click rates below average | Use the name in the subject and adapt the content by signup source |
| Irregular frequency | Spam complaints after months of silence | Build a calendar four weeks ahead |
| Subject that does not match the content | High open rate and low click rate | Write the subject after the email body |
| Several goals in the same email | Clicks split between links | One goal and one main button per send |
| Essential information inside the image | Low clicks with no apparent cause | Put price, deadline and button in text, with alt text on images |
| Never cleaning the list | Progressive drop in delivery rate | Remove inactive contacts and bounces every three to six months |
| Not authenticating the domain | Emails in spam from the first send | Set up SPF, DKIM and DMARC before the first send |
| Hiding the unsubscribe link | Spam complaints above 0.3% | Visible, legible link in the footer, with one-click exit |
Email marketing and data protection law: what is required?
The LGPD requires free, informed and unambiguous consent for a specific purpose. In practice, this translates into four concrete obligations for anyone doing email marketing:
- Inform in the form what the person will receive and how often. Law 13,709/2018 determines, in Article 8, that generic authorizations are void.
- Record the consent, with date, source and what was disclosed. The burden of proof lies with whoever collected the data, not with the data subject.
- Allow revocation at any time, through a free and easy procedure. That is exactly the unsubscribe link in the footer.
- Delete the data when requested, without keeping the contact in a parallel list.
A serious email marketing tool already records consent and processes unsubscribes automatically. What is left for you is to write the form clearly and not import contacts from anywhere.
How to use email marketing to sell digital products
For anyone selling courses, ebooks, mentorships or communities, email marketing is the channel that connects the audience to the sale without depending on paid media or social media reach.
The logic is simple: the person comes in through the lead magnet, is nurtured by the sequence and receives the offer when they already understand the value of what you do.
In practice, two flows already cover a good part of the result: the welcome flow, which introduces you and delivers the first value, and the cart recovery flow, which rescues those who reached the checkout and stopped. If you are still working toward your first online sale, start with these two.
The nurturing sequence comes later, when you already know which objections come up.
The next step is having somewhere for the sale to happen.
On Hotmart, the all-in-one platform for creators, you create your account with no monthly fee and no signup fee: the platform only earns when you sell, as explained in Hotmart pricing.
For email, Hotmart Send is free to use and brings contacts who abandoned the cart straight into your flows, with no manual integration. Create your free Hotmart account!
References
- GOOGLE. Email sender guidelines. Google Workspace Admin Help. Available at: support.google.com/a/answer/81126
- LITMUS. State of Email Reports. Available at: litmus.com/state-of-email-reports
- COMPUTERWORLD. Unsung innovators: Gary Thuerk, the father of spam. Available at: computerworld.com
- BRAZIL. Law No. 13,709 of August 14, 2018. General Personal Data Protection Law (LGPD). Available at: planalto.gov.br
What is email marketing?
Email marketing is sending commercial or relationship messages to a list of contacts who agreed to receive them. It is used to inform, nurture, sell and win back customers, and it differs from spam by a single criterion: the consent of the person receiving it.
What is the difference between email marketing and a newsletter?
A newsletter is a type of email marketing, not a separate category. It has a fixed periodicity and a focus on content, while email marketing is the name of the whole channel, which also includes offers, welcome emails, cart recovery and reactivation.
Can I buy an email list?
No. The LGPD requires free, informed and unambiguous consent from the data subject, and a purchased list has no such consent. Beyond the legal issue, contacts who do not recognize your sender mark the message as spam, which sinks your reputation and hurts delivery even to people who did authorize you.
How often should I send emails?
There is no universal number. What works is defining a frequency you can sustain with quality, stating it on the signup form and sticking to it. For beginners, one send per week or every two weeks is usually enough to keep the list active without driving unsubscribes.



