Lesson 8: What is email warm-up?

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In this lesson, you’ll learn what warm-up really is and what actually happens behind the scenes when you run it inside Woodpecker. You’ll understand why warm-up is fundamentally about building trust with email service providers – and why that trust determines whether your emails land in the inbox or spam.

If you’re starting with a fresh domain, I’ll also share a practical recommendation on how long to warm up before gradually introducing cold outreach, and explain why warm-up acts as the foundation of your entire email infrastructure.

In this lesson, you’ll learn:

• How warm-up works behind the scenes in Woodpecker – your email account joins a network that automatically sends, receives, replies to, and positively engages with emails, simulating the kind of healthy activity that tells email providers you’re a legitimate sender
• Why keeping warm-up running continuously after the initial period matters – those ongoing positive interactions actively counteract the negative signals that cold outreach inevitably generates over time
• Why the commonly recommended two-week warm-up is a shortcut driven by agency economics rather than what actually builds lasting deliverability – and why two months is a far safer foundation before you start sending cold emails in month three
• That warm-up is ultimately about building trust, and trust takes time – a shaky foundation means you’ll be fighting deliverability problems constantly instead of focusing on results

Welcome to my lesson on warm-up!

Here you will learn what happens behind the scenes when you run a warm-up in Woodpecker.

First of all, Warm-up, is the process of building trust with an email service provider. 

To build trust with an email service provider you need to show that you are a legitimate sender.

It basically revolves around showing that your emails are welcomed.

This is not that easy to do with cold outreach as it is with, for instance, newsletters. 

You do not have the opt-in from your recipients.

They simply do not expect an email from you.

So first of all you need to have all your authentication in place to signal that you own the domains

I covered that in the earlier lessons, make sure you watched these.Secondly, your emails need to be welcomed. 

In practice this means your recipients interact and engage with your emails in a positive way. 

They open them, they reply to them, just like you would when writing with friends and colleagues. Warm-up is the process to emulate those positive interactions. 

As I mentioned in the previous lesson, nowadays these processes are automated. 

When your email account is added to a warm-up network it will be prompted to send emails to other email accounts in that network. Those email accounts then reply to your emails and you reply to theirs. 

Additionally, other positive interactions are emulated like:

• taking your email out of spam
• marking your email as important
• opening your email multiple times

and so forth. So this process is called warm-up.

But why is it called “warm” – up specifically? 

Well in the early days warm-up was used only on new email accounts. 

And because they needed to be “warmed” up to the email service provider the industry adopted this type of terminology.

Nowadays, it’s common practice to keep the warm-up on even after the initial few weeks. 

This is because the warm-up emails provide a steady stream of positive interactions.

Those positive interactions counteract negative interactions you may get from your cold outreach. 

We will cover that in more detail in the reputation section.

When we started Woodpecker it was common practice to warm-up a new domain for at least 3 months.

Today, you will most likely encounter the advice of doing a 2-week domain warm-up only.

This is mostly advice given from lead generation agencies that need to provide value for their clients asap. However the medium with which they provide value, the email account, needs to be warmed-up to be trusted and deliver emails to the inbox.

So what do they naturally do? They try to cut the warm-up as short as possible. 

And, if you recall, I said that warm-up is the process of building trust. 

And building trust takes time.

Now no-one can tell you exactly how long you need to warm-up for perfect deliverability but generally, the longer the better. 

If I would have to give you a number I would recommend you warm-up a fresh domain for 2 months.

Then slowly start to introduce some cold emails in month 3. 

Your warm-up is like a foundation.

If your foundation is shaky you will have to work extra hard to keep your deliverability healthy.

Alright that covers what warm-up is in a nutshell. 

Now, in this lesson I mentioned the word trust a lot.

Trust in the email world is also called domain reputation.

Let’s cover that next, see you there.