If you're looking for a free email warmup tool for cold outreach, you have options, but they come with real tradeoffs.
The best free email warmup options in 2026 include Mails.ai (free warmup bundled with their cold email platform, Gmail only), EmailWarmup.com by Maxify (free but limited to 1 mailbox and 10 emails/day), and TrulyInbox (free forever plan with limited daily volume).
For cold outreach specifically, free trials from paid tools like Mailivery ($29/month, 7-day free trial, unlimited mailboxes) and Warmy.io tend to deliver better results because they use higher-quality warmup networks.
The biggest risk with completely free tools is a small or low-quality inbox pool that doesn't build real reputation with Gmail and Outlook.
This guide breaks down every free and free-trial warmup option available right now, explains what to watch out for, and helps you figure out which one actually makes sense for your situation. If you're new to warmup entirely, start with our definitive email warmup guide first.
Before diving into each tool, here's how they stack up side by side. We'll go deeper on each one below.
These tools offer warmup at no cost. The catch is usually network quality, provider coverage, or volume limits.
Price: Free warmup (bundled with cold email platform)
Mails.ai is a cold email outreach platform that includes free warmup for Google Workspace and Gmail accounts. You can warm up an unlimited number of inboxes, which is generous. Since Mails.ai is a cold email tool at its core, the warmup network is made up of other cold emailers on the platform, similar to how Instantly handles warmup.
The upside is that warmup is genuinely free and you get unlimited inboxes. The downside is that you're warming up inside a network of other cold senders. If providers start recognizing the patterns across Mails.ai users (which happens with any large cold email platform), the warmup effectiveness can drop. It also only works with Gmail accounts, so if you need to build reputation with Outlook or other providers, you're out of luck.
Best for: Gmail-only cold emailers who want warmup bundled with their outreach platform at no extra cost.
Price: Free plan (limited), paid plans available
EmailWarmup.com, built by Maxify, offers a free plan but it's more limited than it first appears. The free tier only includes one mailbox and caps you at 10 warmup emails per day, which is barely enough to move the needle on sender reputation.
They do have some useful features like a "Volume Ramp" that gradually increases sending, and they offer deliverability consulting on paid plans. But on the free tier, the combination of one mailbox and 10 daily emails means you're not generating enough engagement volume for providers to notice. It's essentially a taste test, not a real warmup solution.
Their paid plans unlock more features including personalized warmup that mirrors your actual campaigns, which is a solid approach. But at that point you're comparing paid vs. paid, and the free plan alone won't get the job done for cold outreach.
Best for: Testing what warmup looks like before committing to a paid plan. Not enough volume on the free tier for real cold outreach.
Price: Free forever plan (limited), paid plans from $29/month
TrulyInbox offers a free forever plan that lets you warm up one inbox with 10 warmup emails per day. It also supports warmup for email marketing platforms like Mailchimp and GetResponse, which is unusual.
The issue with the free plan is the reply rate. You only get replies to about 10% of your warmup emails, which is too low to send meaningful engagement signals. Providers want to see that people are interacting with your emails. 10 warmup sends with 1 reply doesn't move the needle. You should aim for at least 30% reply rates on warmup.
It's not a bad starting point if you want to test warmup before committing to a paid tool. But you'll likely need to upgrade or switch to something with better engagement if you're doing real cold outreach.
Best for: Beginners who want to test warmup at zero cost before committing.
If you're serious about cold email, these tools offer free trials that let you test a higher-quality warmup network before paying. The difference in network quality between these and the fully free tools is significant.
Price: 7-day free trial, then $29/month (Starters), $79/month (Professional), $199/month (Business)
Mailivery isn't free, but it's the best value in the warmup space if you manage multiple inboxes. Every plan includes unlimited mailboxes, which matters because most competitors charge per inbox. An agency warming up 20 inboxes pays $29/month total with Mailivery vs. $380+/month with per-inbox tools.
The 7-day free trial on the Starters plan includes all features, so you can test the full warmup experience before paying anything.
One thing worth noting: Mailivery is the only warmup tool that includes every feature on every plan. Warmup, blacklist monitoring, email verification, custom templates, API access, team management with roles and shared dashboards. All of it. The only difference between plans is daily warmup volume. Most competitors lock their best features behind higher-priced tiers, so you end up paying more just to get the tools you actually need. With Mailivery, there's no feature gating.
What sets Mailivery apart from free tools:
See how Mailivery's warmup works step by step, or go straight to pricing.
Best for: Cold email teams, agencies, and anyone managing multiple inboxes who needs reliable warmup without per-inbox pricing.
Price: 7-day free trial, paid plans from $49/month
Warmy.io offers a 7-day free trial with a limited number of daily warmup emails. Setup is beginner-friendly with decent reporting and automation. A standout feature is its two warmup networks: one for B2B and one for B2C. Most tools only cover B2B, so this adds flexibility if you send both types of email.
Warmy works well for solopreneurs warming up a single inbox. But if you're doing large-scale outreach or managing lots of client inboxes, the per-inbox pricing adds up fast and there are some concerns about warmup pool quality at higher volumes.
Best for: Solo senders who want easy setup and B2B/B2C flexibility.
Price: 14-day free trial (with Lemlist subscription), standalone from $29/month
Lemwarm is the warmup tool from the Lemlist team. It connects your inbox to a network of real users across 100+ countries and generates personalized conversations. The "Smart Cluster" feature lets you tailor warmup emails to your industry, which makes the engagement look more natural to providers.
The catch is that Lemwarm is tightly tied to the Lemlist ecosystem. If you already use Lemlist for cold outreach, adding Lemwarm makes sense. If you don't, you're paying for a warmup tool that works best inside someone else's platform. It also charges per inbox, which gets expensive at scale.
Best for: Lemlist users who want warmup integrated into their existing outreach workflow.
Price: Warmup included with paid plans from $30/month
Instantly includes email warmup as part of its cold email platform. The warmup network has over one million real email addresses and includes features like slow ramp-up, read emulation, and a deliverability dashboard that shows where your emails are landing across providers.
Like Mails.ai, Instantly's warmup runs inside its own cold email user network. The advantage is the network is massive (1M+ inboxes). The disadvantage is the same one that applies to any platform where warmup lives alongside cold outreach: providers can eventually learn to recognize the patterns. Still, Instantly's size gives it more staying power than smaller platforms.
Best for: Teams already using or considering Instantly for cold email who want warmup bundled in.
For cold email, probably not. Some could even damage your sender reputation. Here's why.
Free warmup tools typically send and reply to generic messages using a small, low-quality network of inboxes. They don't have the resources or business incentive to maintain a high-quality warmup pool. Running a network of real, aged, actively monitored inboxes costs money, and completely free tools have to cut corners somewhere.
Cold email platforms that bundle "free" warmup (like Mails.ai and Instantly) are a step up because their networks are larger. But you're still warming up inside a pool of other cold senders, which is a fundamentally different thing than warming up against a dedicated network of real, diverse inboxes built specifically for reputation building.
If you send email newsletters or transactional emails to people who opted in, a free tool might be fine. The bar for deliverability is lower when recipients expect your emails.
But for cold email outreach, the stakes are higher:
The honest math: a $29/month tool with unlimited inboxes (like Mailivery) costs less than losing a domain to spam placement. If cold email drives revenue for your business, warmup is not the place to cut costs.
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Email warmup is a delicate practice. Use the wrong tool, and you risk your domain reputation. Before picking any tool (free or paid), run through this checklist:
For a deeper dive into evaluating tools, see our guide on how to pick the right email warm-up tool.
Free warmup tools exist and they can work for basic use cases like newsletters or testing the waters. But for cold email outreach where deliverability directly impacts revenue, the free options have real limitations that can cost you more than a paid tool would.
If you're managing multiple inboxes, Mailivery's unlimited mailbox pricing means you're paying less per inbox than any competitor, and the 7-day free trial lets you test everything before committing. For a full breakdown of all the top warmup tools (not just free ones), check out our best email warm-up tools comparison.
Start your 7-day free trial with Mailivery
Most completely free warmup tools use small, low-quality inbox networks that don't build real reputation with Gmail or Outlook. Cold email platforms that bundle free warmup (like Mails.ai or Instantly) have larger networks, but you're warming up inside a pool of other cold senders rather than a dedicated warmup network. For serious cold outreach, a paid tool with a quality dedicated network is a safer choice.
For a free option bundled with a cold email platform, Mails.ai works if you only use Gmail/Google Workspace accounts. TrulyInbox offers a free forever plan that works across providers but limits you to 10 warmup emails per day with low reply rates. For better results, Mailivery's 7-day free trial gives you access to a full-featured warmup with a high-quality dedicated peer-to-peer network.
Mails.ai offers free warmup for unlimited Gmail inboxes as part of their cold email platform. EmailWarmup.com by Maxify has a free plan but it's limited to one mailbox and 10 emails per day. Mailivery offers unlimited inboxes on all paid plans starting at $29/month with a 7-day free trial.
Most domains need 2 to 4 weeks of dedicated warmup before starting outreach. During warmup, you should not send cold email at all for the first two weeks. After that, you can gradually introduce light cold email volume while keeping warmup running. See our email warmup guide for a detailed day-by-day schedule.
Cold email platforms like Mails.ai and Instantly warm up your inbox by exchanging emails with other cold senders on their platform. A dedicated warmup tool like Mailivery uses a network built specifically for warmup with real, aged, diverse inboxes that aren't simultaneously running cold campaigns. Dedicated networks tend to produce more natural-looking engagement signals because the inboxes aren't also being flagged for cold outreach activity.
Mailivery is not a free warmup tool. It offers a 7-day free trial on the Starters plan ($29/month) that includes all features and unlimited mailboxes. After the trial, you choose a plan based on how much daily warmup volume you need. Plans go up to $199/month for teams needing 2,500 warmup emails per day.
The easiest way to get responses to your cold emails.
