Our Review of Lemwarm, the email warm-up tool from Lemlist

Why Lemwarm, Lemlist’s warm-up tool, and what’s it really worth? To understand the value of this type of tool, let’s take a step back. The obvious observation is that it has never been easier to conduct large-scale email prospecting. B2B databases that cost a fortune ten years ago are now accessible to all: tools such as La Growth Machine, Lemlist, Apollo or Clay give you access to hundreds of millions of contacts, enriched, verified and ready to be contacted in just a few clicks.

As a result, everyone started cold emailing, and that’s precisely the root of the problem.

Because Gmail, Outlook and other e-mail providers have seen the wave coming. Faced with the explosion of automated mailings, they have tightened their filters, refined their algorithms and learned to spot suspicious senders with a few signals. A new mailbox that starts sending fifty emails a day? Spam, no warning. Many have experienced this and continue to do so.

To get around this wall, the email warm-up was born. The principle is simple: gradually warm up your boxes to inspire confidence before launching your real campaigns.

The warm-up in 2026 immediately raises a question: does it still work? Or have suppliers also learned to detect it? In this article, we take a closer look at the subject, tell you what warm-up can and can’t do in 2026, and see whether Lemwarm, Lemlist’s tool, is really worth a look.

Our opinion on Lemwarm in brief

What exactly is the email warm-up for?

Before judging Lemwarm, it’s important to understand the problem it sets out to solve.

When you send a commercial email, the recipient’s provider (Gmail, Outlook, Yahoo) doesn’t look at what you write first, it looks at who you are. In concrete terms, it evaluates the reputation of your domain and your sending address. A recent domain (or a box that has never sent anything) has no history. For Gmail, it’s a stranger, and a stranger who suddenly starts sending fifty e-mails a day looks an awful lot like a spammer.

Email warm-up solves this problem upstream. The principle: gradually increase the volume of mail sent from a new box, by generating exchanges that resemble real correspondence. Emails are sent out, opened and replied to, and removed from spam if they land there. After a few weeks, your domain has built up a legitimate sender history. You no longer arrive as a stranger the day you launch your real campaigns.

This is one aspect of deliverability, not the whole of it. Warm-up builds reputation, but sloppy DNS authentication, a dirty contact list or questionable content can undo it all. We’ll come back to this below, because this is precisely where many users go wrong.

Will the warm-up still be working in 2026?

The short answer: yes, but less than before and never alone.

It’s important to understand recent history. In 2020, automatic warm-up worked remarkably well. Google and Microsoft gave real weight to the engagement signals generated by these tools. A box warmed up for three weeks arrived cleanly inbox. Those days are over. By 2024, the two providers had identified the IP address ranges and network patterns of the main warm-up services and mechanically reduced the weight of these signals.

Manual warm-up and peer-to-peer warm-up continue to work, because they generate real send signals between real people. The weak link is synthetic pool warm-up, those networks of fake accounts or AI-generated boxes sold by some of the tools on the market. Gmail has learned to recognize and devalue them.

This distinction works in Lemwarm’s favor, as we’ll see: its network is based on real Lemlist users, but it also imposes a conclusion: in 2026, plugging in a warm-up tool and believing the problem is solved is a mistake. The tool is a starting point, not a turnkey solution. .

How Lemwarm works

Lemwarm is the warm-up tool developed by lempire, the publisher of Lemlist, one of the most established cold email platforms on the market.

Here’s what it actually does once activated.

A network of real users, not phantom accounts

This is Lemwarm’s technical highlight, and it follows directly from what we’ve just seen. Where many services use fake accounts to artificially inflate activity, Lemwarm circulates your warm-up emails through a network of real, verified Lemlist user addresses. Your messages interact with real recipients, sending suppliers a much more credible signal than a synthetic pool.

The important thing is that exchanges are not isolated emails with no head or tail. Lemwarm structures its conversations into real threads, just like normal correspondence. This simulates a natural sending pattern, where some competitors send replies that don’t even resemble real replies. The network covers more than 20,000 domains in over 150 countries.

An easy-to-read deliverability dashboard

Once Lemwarm has been activated, you can track your sender health via a deliverability score ranging from 0 to 100, updated daily and displayed with a clear color code from red to green. The score is based on warm-up engagement, technical configuration and blacklist checks.

Graphs show the evolution of inbox placement versus spam over time, so you can see at a glance whether your reputation is improving.

Integrated DNS technical inspection

Lemwarm checks your technical configuration: SPF, DKIM, DMARC, MX records and personalized tracking domain. This is invaluable, because this is often where the real deliverability problems lie, long before the warm-up itself.

The tool also signals spam risk alerts based on your sending behavior and the content of your emails.

Warm-up on your real templates and Smart Content

Lemwarm lets you heat up your boxes with your real campaign templates, not just with filler text.

On the top level, a content algorithm generates unique objects and message bodies for each exchange, shaped by your sector via a questionnaire.

The idea: to make warm-up emails feel like real prospecting, rather than just noise.

Where Lemwarm shows its limitations

In our opinion, Lemwarm has three main limitations:

• Entry plan volume ceiling. The Essential plan limits warm-up to 40 emails per day. If you follow the community rule of keeping warm-up volume between 10 and 50% of your cold email volume, this limits you to a fairly modest actual send. For a solo start-up, this is sufficient. For a team looking to ramp up quickly, it’s short.
• The Smart Cluster feature, which is supposed to match you with warm-up partners relevant to your sector, doesn’t always live up to its promise.
• Lemwarm focuses on warm-up automation and monitoring, but offers no real inbox placement testing. You can’t send a test email and see exactly whether it lands in Main, Promotions or Spam, depending on the provider. For that, you need a dedicated tool.

Summary of advantages and disadvantages:

Best practices for keeping mailboxes warm

Lemwarm, or any warm-up tool for that matter, will only work in a certain context. Here’s what really makes the difference today, and what the tool alone won’t do for you.

Lemwarm prices: how much does it cost?

This is where the whole decision comes in, because the price of Lemwarm depends on just one thing: are you already a Lemlist customer or not?

Lemwarm standalone

Purchased on its own, without a full Lemlist subscription, Lemwarm offers two plans, billed per email address and per month:

Lemwarm included in Lemlist

If you’re already on Lemlist, the game changes completely: Lemwarm is included at no extra cost in all paid plans. The Email plan starts at €31 per user per month on an annual basis, and the Multichannel plan at €87. In both cases, warm-up runs automatically on your connected mailboxes, with no separate configuration or additional line on the bill.

Our verdict: Who’s Lemwarm for?

Lemwarm is a good warm-up tool. Not the most powerful on the market, not the cheapest to buy in isolation, but reliable, readable and backed by a real network of users.

Lemwarm is for you if :

• You’re already a Lemlist customer: it’s included, so activate it without thinking.
• You work alone or in a small team with a reasonable volume of shipments
• You want a simple tool, a clear score, and you intend to complement it with manual best practices.
• The deliverability of your cold email campaigns is a real issue for your business

Skip it if :

• You’re not with Lemlist and looking for the cheapest warm-up: alternatives are more competitive
• You need a real advanced inbox placement test, which Lemwarm doesn’t offer.
• You’re sending very large volumes and the ceiling of the entrance plan is bridling you
• You expect a tool to take care of your deliverability on its own. Spoiler: none of them do in 2026!