Email Warm-Up Done Right: 2025 Edition

Have you experienced trouble with your email sendings, like all of a sudden being flagged as spam? This problem is more common than you might think. A friend of mine, an online consulting business owner, once got blacklisted by Google. He spent precious time to figure out that the reason for it was his manual bulk email sendings to potential clients soon after he activated his company’s mailbox. To avoid such issues, you should learn why you must implement your email warm-up and how to do it right. 

Email warm-up is a crucial process that ensures your emails reach inboxes instead of spam folders. Whether launching a cold email campaign or setting up a new email account, warming up your email correctly can significantly improve deliverability. In this guide, we’ll cover email warm-up, why it matters, how to do it effectively, and common mistakes to avoid.

To make a long story short, you will learn what effective email warm-up tools are. Now, let’s learn…

What Is Email Warm-Up?

All right, email warm-up is the process of gradually increasing the number of emails sent from a new or inactive email account to build the sender reputation. The trick is that email service providers (ESPs) constantly monitor sending behavior; sudden spikes in email volume can trigger spam filters, even if you never meant it. Warming up your email allows you to establish trust among your recipients and improve inbox placement. The key is to develop a correct email warm-up strategy for the best of your business.

Why Does Email Warm-Up Matter?

According to Lemlist, there are numerous advantages that email warm-up brings. Based on this and other research, we have defined four key benefits that a proper email inbox warm-up can provide:

• It improves deliverability: A well-warmed-up email account has a better chance of landing in the inbox instead of spam. Look at this from the other side to see how it works: you constantly get emails from your friends and business partners, let alone from your subscriptions. However, you rarely get notifications from various unknown—and unwanted—senders. Your spam filters protect your privacy and your time.
• It builds sender reputation: The quality of statistics measures your success if you build trust among recipients. ESPs evaluate how they interact with your emails (opens, replies, spam complaints), and a good reputation leads to better deliverability. There’s a correlation between good stats and good deliverability. 
• It prevents blacklisting: Sending a large volume of emails too quickly can flag your account as suspicious, leading to blacklisting. Just recall the case with my friend I mentioned in the intro—and don’t repeat his mistake! 
• It ensures compliance: Do you know that some email providers have sending limits for new accounts? This is why warm-up helps you stay within these limits while gradually increasing volume.

How to Warm Up Your Email for Maximum Deliverability

There are two ways to warm up your email. The first one is a manual warm-up, and the second one is an automatic warm-up. In this section, we’ll cover both approaches. 

Manual email warm-up

These are five steps to take if you want your manual email warm-up to be a success story:

1. Start small: “A journey of a thousand miles begins with a single step.” We strongly recommend you begin the process by sending a few emails (five to ten messages per day) to engaged contacts who will definitely open and reply. This is the way to send a message: I am not spamming! 
2. Increase gradually: Scale up by 10–20% daily while monitoring engagement. Again, this pattern has nothing to do with spam-sending models, so such a moderate escalation will build your reputation as an honest sender. 
3. Engage with replies: Here’s the question: How do you prove that you are not a spammer? The best way to state that you are not a spammer is to encourage recipients to reply, mark emails as important, and move them to the inbox.
4. Avoid spam triggers: Don’t overweigh your messages! Use personalization in your content and avoid excessive links, images, or sales-heavy language. Make your communication sharp and clean.
5. Monitor metrics: Keep an eye on the stats by tracking open rates, reply rates, and spam complaints to adjust your email warm-up strategy accordingly.

Automated email warm-up

What can you do if you don’t have time to warm up your inbox manually? You can use various email warm-up tools to automate the process. It will gradually increase email volume and simulate real-life user interactions. Such an approach can save plenty of time and help you devote your efforts to your core business activities. On the other hand, you must allocate a budget, as most such services are payable. Let’s see what some popular warm-up tools are:

• Warmbox: This email warm-up solution’s features are fully customizable, and the UX is very friendly, according to some customer reviews. Warmbox offers plenty of email warm-up features, like automated interactions, spam auto-remove, and many others. The tool also has a free IP blacklist & DNS settings checker. Warmbox’s pricing starts at $15/month per email account with the Solo plan, which is a single inbox solution. More sophisticated plans include three and six inbox options, plus a flexible solution for larger teams.
• Lemwarm: This email deliverability tool also has various pay-as-you-go plans, with pricing starting at $24/month per email account for the Essential Plan. As the warm-up options are rather typical compared to other services, Lemwarm has a couple of curious features, like Lemwarm ROI simulator and Deliverability Master Class. 
• MailReach: This email warm-up tool promises high deliverability rates and great ROI using its smart AI warming algorithm. Pricing depends on the number of mailboxes being warmed up, starting at $25/month per mailbox.

Please consider that the aforementioned solutions offer interactions with all major email service providers, like Gmail, Outlook (Microsoft 365), YahooMail, iCloud, Amazon SES, AOL (Verizon), and any other SMPT inboxes.  

Chart: Optimal email warm-up schedule

Now, let’s do some science or magic, depending on what you expect from a good email warm-up solution. 

Below is a professional, research-based, and detailed email warm-up 30-day schedule demonstrating the number of emails sent and the optimal quantity based on hourly and daily limits. Such an approach would help you escape being listed as a spammer while sending a considerable number of messages to your contacts. 

This example describes a monthly model with a sustainable increase in daily emails: 

*Please note that the suggested email volumes may vary depending on the email service provider you are targeting. Make sure to carefully study the guidelines provided by the ESP for the most correct and up-to-date information. For instance, Gmail suggests the following email frequency. 

Consider this: the sustainable but gradual increase in emails ensures ESPs perceive the sender as a legitimate and trustworthy user. As you can see, the total per day growth is awe-inspiring, from only 480 emails on Day 1 to a whopping 112,656 messages on Day 30, which is more than a 234-fold increase! The same massive quantitative increase works for hourly limits, from 20 on Day 1 to 4,694 on Day 30. 

Please also note that it is essential to space out emails hourly and daily because it prevents sudden spikes and jumps that could trigger spam filters. Imagine if you had applied the Day 30 tactics on Day 1: you would be immediately blacklisted as a spammer. This approach is a good example of a best practice based on insights from established email deliverability experts (you will also find the full version of the table here).

Common Email Warm-Up Mistakes to Avoid

Let’s look at the five most typical mistakes you must avoid when planning your email campaign:

• Sending too many emails too soon: We are sure you know it already, but we must remind you that rapid and uncontrollable scaling will inevitably lead to spam filtering.
• Ignoring engagement: Don’t miss the road signs because low open and reply rates signal poor sender reputation.
• Using spam-friendly content: Email warm-up is a great time to show good copywriting skills when developing your content. Note that words like “free,” “discount,” and excessive capitalization can hurt deliverability. Try to avoid writing sentences like this: “Hurry up to check out our GREAT DISCOUNTS and FREE OFFERS!”
• Skipping warm-up for new domains: You also should know that new domains need reputation-building before full-scale emailing. 
• Neglecting monitoring tools: We recommend using as many email marketing tools as possible. Please note that email service providers give comprehensive feedback through tools like Google Postmaster Tools and Microsoft SNDS, among other available options. 

To Sum Up

We hope you have warmed yourself up enough to get to the finish line of this review! We also hope the question, “How to warm up an email?” now has a clear answer. 

As you can figure out now, proper email warm-up is a must for successful email campaigns. There are two approaches for email warm-up: manual and automated. Whether you use manual methods or automation tools, following a structured warm-up process will boost deliverability and help your emails land where they belong—the inbox instead of spam. Follow our recommendations: stick to best practices, avoid common mistakes, and monitor performance to optimize your email outreach.

So, if you don’t want to end up landing in the spam folder, ruining a digital marketing campaign, just like the guy from the real-life case mentioned in the intro, use our recommendations as your guidelines for a successful email warm-up!