What is an Email Warm Up Tool?

If you're in sales or marketing, you should care about cold email deliverability and know about warming up a new domain. In this blog, we go over essential email warm up tools for everyone.
Cold emailing is a great way to connect with prospects, create rapport and generate leads, but it’s not easy. Creating an effective cold emailing campaign takes time, dedication, and strategy.

Fortunately, some tools make this process a little less challenging.

Warm-up tools help get your email campaigns in your prospect’s inboxes and avoid the spam folder.

They provide everything to detect your domain’s flaws: such as SPF/DKIM/DMARC not set, to which email provider you're hitting inbox, improve your sender reputation, and warm up your email to hit the inbox effectively. All of which are essential for a successful cold emailing outreach.

Use these tools beforehand to warm up your email, streamline your efforts, and see even greater results from your cold emailing campaign.

What is Email Warm Up?

Email warm up is the process of gradually gaining the trust of Email Service Providers (ESPs).

For the greatest user experience, most ESPs have implemented powerful spam detection algorithms.

They are frequently called "spam filters" and scan your email for any strange information. Anything that appears suspicious is instantly removed and classified as spam.

Any emails sent by a new domain in high quantities will all land in the spam folder.
Sending automated (or manually generated) emails, which are then replied to (again through the system) to demonstrate interaction, warms up your domain.

This totally automated method "warms up" your domain. All emails seem trustworthy enough to gain the ESPs' trust.

To promote business conversations and trick email service providers (ESPs), most email warm-up solutions used today rely on AI machine learning supported by a large network.

A proper email warm up requires progressively increasing the number of emails sent while maintaining high engagement rates to convince ESPs that you are a reliable and entertaining sender who merits being in the recipient's primary inbox.

Tip: Warming up your domain consistently throughout email campaigns helps increase email deliverability and improve the efficiency of your entire campaign.

Email Warm Up Tool - Definition

An email warm-up tool is an independent software or an email automation program feature that helps improve your email address's reputation and gradually increases your daily email-sending capacity.

Without an email warm-up tool, you can't send a whopping 1000 emails from your new or current email address on day 1 because email service providers have placed daily limits for newer email addresses.

Users of Google Workplace, for example, are restricted to 2000 emails per day. Many email service providers have implemented these restrictions to stop spammers.

If you start sending emails often, the moment you receive a new email address, your email server might suspend your account, or other servers' spam filters may label your emails as spam.

Why Does Your Domain Need Email Warm Up?

Warming up your inbox is primarily done to improve email deliverability and maximize the outcomes of your cold email campaigns. Ultimately, increased open, reply, and click rates result from a warmed-up inbox.

Your sender reputation improves while your domain is warmed up, making it simpler for your emails to reach your prospect’s primary mailbox.

5 advantages of warming up your inbox:
  • Warming up your inbox showcases your engagement rates because inbox placement is mostly based on engagement.

  • You can control your sender's reputation and deliverability by warming up your email.

  • As soon as your campaign is launched, you'll notice an increase in open rates because your warmed-up domain will make you more visible.

  • Your sender's reputation grows as you go through the email warm-up process as ESPs determine the trustworthiness of your domain.

  • The highest deliverability on a warmed-up domain results in lower bounce rates. Your prospects will receive all of your emails in their primary inbox.

Best Tools to Test & Improve Email Deliverability


GMass is an email marketing tool that works as a Gmail and Gsuite plugin.

This tool provides 8 different products that are all targeted at your needs for cold outreach (SMTP tester, email verifier, email tester, etc.)

Their warm-up tool is the only one of their 8 items that is cost-free. The fact that it is only compatible with Gmail and Gsuite, and they are not customizable, are the only drawbacks.

You will need to find different warm-up tools if you use other domains. Additionally, you must subscribe to their paid service if you wish to use any of their other services.


GlockApps guarantees email deliverability for all primary email service providers like Gmail, Outlook, Apple Mail, etc.

It concentrates on spam tests and offers in-the-moment data that indicate whether or not your email reached the subscriber or prospect's inbox, was marked as spam, or was never delivered at all.


Unfiltered is an email warm up tool specifically for salespeople, because we could not find one that successfully fulfilled all of our needs, fast enough.

Warm will accomplish this through real email engagement on the back end. You can use your own email copy to pre-send and engage with campaigns before sending them to your email lists.


SpamCheck by Postmark is a tool that analyzes your email copy and scores you based on its deliverability probability.

Your code can be pasted right onto the website. On a scale of 0 to 5, the system assigns you a score; the closer you are to zero, the better it is.

Sender Score

Sender Score is a service by Return Path. It rates your content on a scale of 0 to 100. It also lets you check the reputation of your IP address.


If you use cold email campaigns, you absolutely need to have an SMTP warm-up tool. Your carefully written sales cold email sequences may not be getting as many opens as you would like if that is the case. The issue is likely with email deliverability.

So, when choosing the tool, be careful that it doesn't ignore the warm-up and instantly boosts your sender reputation in five days. To operate cold email campaigns at scale, the email load must gradually increase until your email address is fully optimized.

With the advice in this article, you can learn how to improve cold email deliverability and be sure that your emails are being received by the people they were sent to.
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