Does Email Warm Up Work & Is It Safe In 2024?

Updated March 2024

Are you wondering if you should use an email warm up tool before sending cold emails?

For many years, people advocated using email warm up tools to improve deliverability. Now, their effectiveness is questionable.

At best, they don’t do much to help, at worst, they could get your emails marked as spam by email service providers.

I’ve been sending cold emails for many years, and have also built a leading cold email software (Emailchaser), so I am qualified to talk on this subject.

In this article, I will cover the following:

- What is email warm up?
- Does email warm up work?
- Are email warm up tools safe to use?
- Is email warm up necessary?

What is email warm up?

Email warm up, also known as email warming, is the process of gradually increasing the number of emails that you send from a new email address.

The reason why some people think that email warm up is a good idea is because most email service providers will think that a sudden increase in email volume from a new email address is suspicious, causing your emails to go to the spam folder.

picture of cartoon man sending an email

If you create a new email address to send cold email campaigns from, and you immediately send hundreds of emails, then your emails will go to spam.

The idea of email warming is to gradually increase the number of emails being sent from your new email address (with automated replies as well). This makes it seem like your new email is active and receiving lots of responses, thus tricking email service providers into thinking that your new email should not go to spam.

If an email address receives a high percentage of replies to the emails it sends, then it will have a good email sender reputation score, which is one of the factors that email service providers use to determine if your emails should go to the primary inbox or spam.

screenshot showing analytics page inside Emailchaser's dashboard

There are many companies that offer email warm up tools that can automate the above process for you. All promising “improved deliverability”, whilst providing very little evidence of any actual results. They will add your email address to a “pool” of other emails, which all send and respond to each others' emails, with the goal of artificially manipulating email service providers into thinking that your email has a high response rate.

Does email warm up work?

The short answer is no.

Trying to artificially manipulate your email sender reputation score with email warm up tools is not effective, and will cause your emails to go to spam as email service providers will blacklist your email and domain.

There are many companies offering email warm up tools, but they don’t offer any evidence showing that they work.

There are many factors that affect email deliverability, and the idea that email warm up is the "silver bullet" of cold email deliverability is a myth perpetuated by companies that sell email warm up services. If you want to learn how to guarantee the best possible deliverability, then I recommend that you read my article How To Send Cold Emails Without Landing In Spam.

Even if email warm up tools were effective, the question of whether they will remain effective long term is debatable since email service providers such as Gmail do not allow the use of them. Email warm up tools are against Gmail’s terms of service.

Google has the world’s most advanced algorithms and AI, that can already detect AI generated text. Do you really think they don’t know when email warm up tools generate fake emails to send to all of the emails in their warm up pool? It is very easy for email service providers to detect emails sent and received from email warm up tools.

Companies that offer email warm up features often point to the number of email accounts in their warm up pool, as if this somehow means that Google and Microsoft can't detect the warm up pool due to the volume of accounts.

The reality is that it is still extremely easy for Google and Microsoft to detect emails from warm up pools, since the type of email accounts found in warm up pools are not representative of the average email account that exists in the real world. For example, virtually all email accounts found in warm up pools will be brand new, and from either Google or Microsoft; it is not difficult to detect when an email account is part of a warm up pool when all of the emails being received are from email accounts that are not even remotely representative of the general population.

Email warm up tools are not effective, and the only people promoting them are financially incentivized to sell you them.

Are email warm up tools safe to use?

Email warm up tools are not safe to use.

Email service providers such as Gmail don’t allow them and will blacklist your email address if you use them. It is against Google’s terms of service to use these tools.

The below tweet shows a statement from Google explicitly stating that email warm up tools are not allowed, and if used, will cause your emails to be marked as spam:

Google goes even further, as shown in the below tweet:

Even the founder of Gmass (popular email warm up tool) admits that email warm up is not safe and has shut down his entire warm up tool:

To summarize, Google (Gmail) and other email service providers are clamping down hard on email warm up tools. These are the most advanced companies in the world, and they can easily identify fake emails sent from email warm up tools. I recommend that you don’t use any email warm up tool, as your emails will likely be marked as spam if you use them.

Also, one of the main factors affecting your deliverability is your total sending volume. Email warm up tools contribute to your overall sending volume, which isn't a good thing. If you don't understand why your sending volume matters, then I recommend that you read my article How Many Cold Emails Can You Send Per Day Before Going To Spam?

Is email warm up necessary?

Email warm up is not necessary. I recommend that you don’t use an email warm up tool before sending cold emails because there is no evidence showing they work.

If you use an email warm up tool, the best case scenario is that it has no effect; the worst case scenario is all of your emails being marked as spam by email service providers.

The best way to avoid spam folders is to follow the advice in my article How To Send Cold Emails Without Landing In Spam.

I also recommend that you use Emailchaser to send your cold emails. Our email sending software is built for deliverability and will help your emails land in the primary inbox (not spam).

screenshot showing Emailchaser dashboard

Email warm up reminds me of Private Blog Networks (PBNs) in SEO. I’ve been doing SEO for nearly a decade, and when I first got started, a lot of people who were selling SEO courses were teaching the use of PBNs to build backlinks to websites. This method was spam (just like how email warm up is spam), and doesn’t work, isn’t long term sustainable, and is easily detectable by Google.

Now, I would never use PBNs as I know how to build quality backlinks from real authoritative websites. The same applies to cold email, I would never use an email warm up tool knowing what I know now.

Even today, you can go to Fiverr and buy 5,000 spammy backlinks from someone. Just because the service is offered, doesn’t mean it is effective or safe. Just because there are people willing to sell you email warming tools, doesn’t mean that they work, are safe or that you should use them.

Final thoughts

Email warm up tools are not effective at improving your email deliverability.

These warming services are also unsafe as they are banned by email service providers such as Gmail. Email service providers will mark your emails as spam if you use warm up tools.

There are many factors that affect email deliverability, and the idea that email warm up is the "silver bullet" of cold email deliverability is a myth perpetuated by companies that sell email warm up services.

If you want to learn how to guarantee the best possible deliverability, then I recommend that you read my article How To Send Cold Emails Without Landing In Spam.

picture of George Wauchope

Article by

George Wauchope

Founder of Emailchaser.

I have been working in the sales & marketing industry for nearly a decade.

When I’m not working on my business, I enjoy eating sushi & doing jiu-jitsu.

About the author
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