What does Email warmup mean?

Email warmup is an important process when you want to ensure that your emails actually land in the inbox and not in spam. Here's a simple overview of what it means and why it's crucial for your email delivery.

Published on 20/04/2026

What is email warmup?

Email warmup is the process by which a new or inactive email account gradually builds credibility with email providers like Gmail, Outlook and Yahoo.

Instead of sending many emails at once, start with a low number and increase the volume little by little. The aim is to show that the sender is legitimate, active and relevant.

When talking about email warmup, it's all about deliverability. That is, the likelihood of your emails landing in the recipient's inbox and not in spam.

The term is often used in the context of cold email, email marketing, sales emails and setting up new domains. But it's also relevant for organisations that want to protect their sender reputation over time.

Why is email warmup important?

Email providers are constantly assessing whether a sender seems trustworthy. If a brand new account or domain suddenly sends out a lot of emails, it can look like spam behaviour.

This can lead to poor inbox rankings, lower open rates and, in the worst case, blocking.

Email warmup reduces this risk. By gradually building up activity, you send positive signals to mail servers. This makes it easier to establish a good sender reputation.

For companies, this means that their emails have a better chance of being read. This applies to sales-related emails, newsletters, onboarding emails and automated messages.

Better chance of landing in primary inbox
Less risk of spam filtering
Stronger sender reputation
Better results on outreach and email campaigns
More stable performance over time

How does email warmup work in practice?

In practice, email warmup is about starting with a few daily emails and slowly increasing the volume. At the same time, emails should be relevant, personalised and preferably create natural interaction such as opens, replies and flagging as important.

Email providers don't just look at the number of emails sent. They also assess how recipients respond to them.

If emails are opened, responded to and not marked as spam, it strengthens the sender's credibility.

A typical warm-up period lasts from a few weeks to a few months, depending on the domain's history, the planned sending volume and the quality of the mailing list.

Typical elements of a warm-up process

Low initial volume with few emails per day
Gradual increase in the number of broadcasts
Using genuine and relevant recipients
Focus on response rate and engagement
Continuous monitoring of bounce rate and spam complaints
Correct technical setup of the domain

The more controlled the process is, the greater the chance of a stable and healthy development. It's not about speed, but about building trust step by step.

Email warmup and sender reputation

Sender reputation is one of the most important factors in email delivery. It is an overall judgement of how trustworthy you appear as a sender.

Mail providers build this reputation based on history, behaviour and recipient reactions.

If you send to invalid addresses, get a lot of spam complaints or have very low engagement, your reputation will suffer. Conversely, stable sending and positive signals will improve your position.

Email warmup is therefore not just a technical exercise. It's a strategic method to create a healthy foundation for future email communication.

Signals that affect your reputation

Opening rates
Reply to emails
Spam flags
Bounce rate
Number of emails sent over time
Domain age and history
Technical authentication such as SPF, DKIM and DMARC

When these elements work together, you build a more robust sender profile. This is especially important if email is a key channel for sales, marketing or customer dialogue.

When should you use email warmup?

Email warmup is especially relevant in situations where you are starting from scratch or changing your sending behaviour significantly. This applies to small businesses, agencies, salespeople and marketing teams.

When you start using a new domain
When you create a new email account for outreach
When an old account has been inactive for a long time
When you want to scale your broadcast volume
When you've had problems with spam or poor delivery performance

Many people make the mistake of thinking about warm-up only after the problem has arisen. But the best effect is achieved by starting correctly from the beginning.

Difference between email warmup and regular email marketing

Email warmup and email marketing are related, but they are not the same. Warmup is the preparation, while email marketing is the actual use of the channel for communication and conversion.

Warmup focuses on building credibility and technical health. Email marketing focuses on message, segmentation, timing and results like clicks, sales and loyalty.

In a nutshell

Email warmup is all about getting the account ready to send
Email marketing is about using email strategically to achieve business goals
A good warm-up sets the stage for successful campaigns

If the foundation isn't in place, even good campaigns can produce poor results. That's why warmup should be seen as an important part of the overall email strategy.

Manual or automatic email warmup

There are basically two ways to work with email warmup: manually or via software. Both approaches have advantages, but they are often used in different situations.

With manual warmup, you send yourself a small number of emails, follow engagement and slowly increase volume. It provides high control, but requires time and discipline.

Automatic warmup uses tools that send and receive emails within specific networks to simulate natural activity. This can make the process faster to manage, but the quality varies from tool to tool.

Pros and cons

Manual warmup for more authentic activity
Automatic warmup saves time and can be easier to scale
Manual approach requires more internal resources
Automated solutions should be chosen wisely to avoid artificial patterns

For many organisations, the best solution is a combination of technical setup, realistic deployment schedule and continuous performance monitoring.

Technical setup behind a good warmup

Email warmup is not just about the number of emails. The technical setup of the domain also plays a key role.

If authentication is not in place, your emails can look suspicious even if you send few and relevant messages.

Therefore, you should ensure that the domain is configured correctly before the warmup begins. This especially applies to DNS settings and security layers that help mail servers verify the sender.

Important technical elements

SPF, which specifies which servers are allowed to send on behalf of the domain
DKIM, which digitally signs emails
DMARC, which tells the recipient server how to handle unauthorised emails
Custom tracking domain if you use email tools with tracking
Consistent sender name and professional signature

Without these elements, even a good warmup can lose impact. Therefore, technique and content should always be considered together.

Typical errors during email warmup

Many companies underestimate the process and send too much too fast. It's a classic mistake that can damage a domain's reputation right from the start.

Another mistake is to use bad or old lists. If many addresses are invalid or recipients are not expecting the email, it will often lead to bounces, ignoring or spam flags.

Too fast upscaling of transmission volume
Sending to unverified email addresses
Missing SPF, DKIM or DMARC
Generic and impersonal messages
Too many links or attachments in the first emails
Failure to monitor delivery data

The better you avoid these mistakes, the stronger your long-term email performance will be. Warmup is very much a matter of patience and quality.

How to measure if email warmup is working

It's important to follow the progress along the way. Email warmup should not be a blind process, but a controlled build-up based on data.

You can look at how many emails are delivered, how many are opened and whether replies are received. You should also keep an eye out for negative signals such as spam complaints and bounced emails.

Inbox placement, i.e. whether emails land in the inbox
Opening rate
Response rate
Bounce rate
Spam rate
Evolution of domain reputation over time

If the numbers look stable and engagement is increasing, that's a good sign. If you're experiencing declining performance, you should slow down and review your content, lists and technical setup.

Email warmup in sales, outreach and lead generation

In B2B sales and lead generation, email warmup has become particularly important. Many companies use email as a channel to create dialogue with potential customers, but competition in the inbox is high.

If your account is not properly warmed up, even targeted and personalised emails can end up in spam. This means fewer responses, lower meeting bookings and lower return on sales efforts.

Warmup is therefore closely linked to outbound strategy. Before scaling outreach, you should ensure that the account, domain and process are mature enough for the load.

Why it's important for sales work

More emails reach the right decision makers
Protecting your domain while working with cold email
Get better data on what works in campaigns
Avoid burning a new channel too quickly

Best practice for a healthy email warmup

The best approach to email warmup is usually simple: start slow, be relevant, and measure everything. It sounds simple, but it requires structure and consistency.

Start with a low number of daily emails
Gradually increase volume week by week
Use verified and relevant recipients
Keep your emails short, natural and personalised
Avoid aggressive sales messages in the beginning
Monitor technical errors and delivery figures continuously
Stop or adjust quickly for negative signals

A successful warm-up is not necessarily fast. However, it does provide a stronger foundation that can pay off in the long run.