Email Warm-Up 101: What It Means, Why It Matters, and How It Works

Email Warm-Up 101: What It Means, Why It Matters, and How It Works

Imagine you’ve got a great email campaign lined up. You’ve planned out a sequence of personalized emails with strong subject lines and CTAs, you’ve got a list of interested leads, and you can’t wait to get started. You hit send, then sit back and wait for the responses to roll in.

Except they don’t. You hear nothing back. Zero replies, zero clicks and zero opens. How is that even possible?

Well, good, personalized emails and a relevant list are important, but none of that matters if your emails aren’t being delivered in the first place. While several factors can affect your delivery rate, one of the most important is your sender reputation.

This is where email warm-up comes into play.

In this post, we’ll take a closer look at exactly what it means, why it’s so important, and the best ways to warm up your email address.

What is email warm-up?

Email warm-up refers to the practice of sending a gradually increasing number of emails from a new email account with the aim of building a positive reputation with email providers and avoiding spam filters.

Previously, it was possible to warm up an email purely based on the number of emails sent. If a brand new email account sends 15 emails on the first day it’s used, that seems reasonable. If it went from zero to a thousand emails in one day, that would look suspicious. As long as the numbers looked right, you could be building a good reputation. 

Today, email service providers (ESPs) take additional factors into account when trying to assess your reputation. Specifically, they’ll look at how recipients engage with your messages. Are your emails being opened, replied to, and marked as important? Or are they being ignored, deleted, and marked as spam? To keep that positive reputation, email warm-up now has to show that recipients find value in your emails. 

When defining email warm-up, there are some important distinctions to make. Warming up a brand new domain (e.g., will take longer than warming up a new email account on an existing domain (e.g., You should think about both when warming up an email address. 

Why do you need to warm up your email?

You might be wondering why you should bother with a separate email warm-up process. After all, if you’re going to be sending emails anyway, why not just go ahead and use your new account to talk with potential leads (at a lower scale to start with)? 

Unlike a traditional email campaign, email warm-up is specifically designed to improve deliverability. Even the best email marketing campaigns to highly engaged lists can still have low open and reply rates. It only takes a couple of people to mark your campaign as spam and you could end up black-listed. 

Consequently, there are several reasons to warm up an email account before using it for outreach.

Email warm-up builds (or repairs) your sender reputation 

As we’ve already mentioned, email warm-up is about building a positive reputation. To ensure that their users have the best experience possible, ESPs like Gmail and Outlook will check a sender’s reputation before allowing their email through.

When you first set up an email account, it has a neutral reputation. From then on, every action that you and your email recipients take will be evaluated and used to score that reputation. Actions that look like normal, everyday activities for an email user (such as sending and receiving a handful of emails each day) contribute to a positive reputation. 

On the other hand, sending a large number of emails that are ignored or marked as spam will lower your reputation. If that reputation falls too far, then ESPs will no longer accept your emails. 

By sending and receiving emails in a natural way, email warm-up helps you build that reputation, whether you’re starting from neutral or trying to repair a damaged reputation.

Email warm-up improves deliverability for sales outreach

There are a lot of factors that go into a high-performing sales email. Unfortunately, the techniques that are used in effective sales emails can raise red flags with ESPs. 

For example, using personalized images in your outreach is a great way to get your reader’s attention. Unfortunately, spammers will also use images instead of words to try and bypass filters. That makes any image included in an email a potential red flag and subject to ESP scrutiny.

Similarly, a sales email will often include a link as part of their CTA, whether that’s to book an appointment or see a product demo. However, while URL shortening services (such as are popular and make your links look a lot tidier than a long complicated string of text, they are also used by spammers to misdirect email recipients to a different address. 

By following email deliverability best practices — such as making sure at least 80% of your message is text and using full links to high-authority domains — you can avoid spam filters. 

If you want to further increase your inbox placement, make sure to do a proper account warm-up using the exact email templates and signatures you will be using for outreach. Getting those messages opened and replied to will give a clear signal to ESPs that those images and links are safe, trustworthy, and can be sent to the recipient’s inboxes.

Email warm-up helps scale your outreach faster 

Although it might seem like a time-consuming process, email warm-up dramatically cuts down the time it takes to build your reputation. Manually warming up your email account can be done in two to three weeks. You can then start sending cold emails, gradually increasing the number of emails every few days (see the sample 3-day ramp-up framework below). 

The process can be completed even sooner by using a dedicated tool and automating those warm-up emails, as we’ll see in the next section.

While you can skip the warm-up and go straight into your email campaign, it’ll be a long time before you start seeing the positive signals that feed that reputation. Even worse, just a couple of unhappy recipients can tank that reputation and make the process take even longer.

How to warm up your email account

There are two main ways to warm up an email account. You can do it by yourself manually or you can automate the process with a dedicated email warm-up tool. 

Manual email warm-up

Warming up an email account manually is often considered the safest option, as you have full control over the process. Simply start sending emails to friendly accounts. 

You can start with email accounts that you own, such as that Hotmail account you still have from school or your personal Gmail account. However, unless you have a large collection of email accounts just hanging around, you’re going to need to get some other people to help out. Reach out to friends, family, colleagues and anyone else who won’t mind doing you a favor. Ideally, you’ll want to email as wide a range of accounts as possible, so you can build your reputation with different ESPs. 

Remember, engagement is also a key factor. Ask the recipients to open up your messages, reply to them, and mark the messages as important. If a message ends up in the spam folder, ask them to move it to the inbox and mark it as safe. 

Warming up your email account this way is free, but it takes a bit of time and patience (as well as some very understanding friends and family). 

Automated email warm-up

If you don’t want to spend hours sending and responding to warm-up messages, you can always use a dedicated email warm-up tool to automate the process. Just connect your email account to the service then sit back and watch your sender reputation grow. 

This is a fast and easy way to build your reputation, but it’s important to choose the right tool. Before signing up for an email warm-up service, check out exactly how they work. Here are some questions to ask when considering different tools. 

  • Do they use real accounts to build reputation or do they use free/temporary email accounts? 
  • Do they send real messages or are they sending unintelligible nonsense text? 
  • Do they just send and receive messages or do they also ensure those messages are properly engaged with? 

All of these can have a real impact on your sender reputation.

Email deliverability checklist (including proven tools)

It doesn’t matter how good your template is or how personal your emails are, if your emails are destined to the SPAM folder.

Follow this checklist to make friends with SPAM filters and ensure top deliverability for your outreach emails.

Moving forward with your email outreach

As we’ve stated earlier, it usually takes 2-3 weeks to get your newly created email account ready for outreach. If you follow a consistent sending schedule and ensure positive engagement, your sender reputation can build up even faster. 

However, this doesn’t mean that you can launch a full-scale cold outreach sequence the very next day. Rushing to increase the number of sent emails will likely result in deliverability issues and can seriously damage your reputation.

In this case, there are two things to consider:

  1. First, gradually increase the sending volume to avoid raising any red flags. You can follow the schedule featured above to consistently increase the number of sent emails on a daily basis, safely scaling your outreach.
  2. Secondly, keep your warm-up enabled even if you’ve already reached the desired delivery rate. By sending automated messages that guarantee high engagement along with your cold emails, you level out possible changes in your sender score.

Final thoughts

While it might not be the first thing you think of when it comes to sales outreach, email warm-up is an essential part of any email campaign. Both before and during your cold outreach, email warm-up improves deliverability and means that prospects are more likely to see your email. 

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