Email Warmup Tools: What They Do and Which Ones Actually Work

If you're sending cold emails at scale, you need email warmup. Without it, your emails land in spam, your domain gets flagged, and your outreach campaigns go nowhere.

Email warmup tools gradually increase your sending volume while simulating natural email activity—sending messages, getting replies, moving emails out of spam. This builds your sender reputation with email providers like Gmail and Outlook so your actual outreach emails hit the inbox.

I've tested most of the major warmup tools. Here's what you need to know about pricing, features, and which ones are worth using.

What Email Warmup Actually Does

Email warmup tools connect to your email account and automatically send emails to other accounts in their warmup network. Those accounts reply, mark your emails as important, and move them out of spam folders. This creates positive engagement signals that email providers use to determine if you're a legitimate sender.

Without warmup, a brand new domain sending 100+ cold emails per day looks suspicious. Email providers throttle your delivery or send you straight to spam. Warmup makes your sending patterns look gradual and natural.

You need warmup for new domains, new email accounts, or any account that hasn't been sending regular email. Even established accounts benefit from ongoing warmup if you're doing heavy cold outreach.

Smartlead Warmup

Smartlead includes unlimited email warmup as part of its cold email platform. You get warmup for unlimited email accounts on all plans, starting at $39/month for 6,000 leads.

The warmup runs automatically once you connect your email accounts. You can adjust the daily sending volume and ramp-up speed. Smartlead's warmup network includes thousands of real email accounts, and the system handles replies, spam folder interactions, and engagement automatically.

What's good: Unlimited warmup accounts included with your subscription. No per-account fees. Built directly into the cold email platform so you're not juggling separate tools. The deliverability monitoring shows your sender score and flags issues.

What sucks: The warmup settings are fairly basic compared to standalone tools. You can't customize conversation topics or email content as much. If you only need warmup without the full cold email platform, you're paying for features you don't use.

Best for: Anyone already using Smartlead for cold email who wants warmup included without extra costs. If you're sending from multiple domains with multiple accounts per domain, this is the most cost-effective option.

Try Smartlead's warmup features

Instantly Warmup

Instantly offers email warmup as part of its cold email software. Plans start at $37/month and include warmup for all connected accounts.

The warmup feature is called Unibox Warmup. It sends emails between accounts in Instantly's network, generates natural-looking replies, and gradually increases sending volume. You can set custom daily limits and adjust how aggressive the warmup should be.

What's good: Simple setup that takes about 2 minutes per account. The warmup runs in the background while you send campaigns. Unlimited warmup accounts on all plans. Good deliverability tracking that shows inbox placement rates.

What sucks: Like Smartlead, you're paying for the full cold email platform even if you only want warmup. The warmup conversations are generic and obviously automated if anyone actually reads them. Some users report the warmup is less effective for Microsoft/Outlook domains.

Best for: Teams running cold email campaigns through Instantly who want integrated warmup. The platform works well if you need both functions in one place.

Check out Instantly's warmup tools

Lemwarm by Lemlist

Lemwarm is Lemlist's standalone warmup tool, though it's also included with Lemlist's cold email plans. Pricing starts at $29/month for a single warmup account, or it's included free with Lemlist Email Outreach plans starting at $59/month.

Lemwarm uses a network of real email accounts to exchange emails with your account. It customizes warmup conversations based on your industry and provides a deliverability score called Lemwarm Score that tracks your sender reputation.

What's good: More natural-looking warmup emails compared to competitors. The conversations actually make sense if someone reads them. Good reporting on deliverability metrics. You can use Lemwarm standalone without the full Lemlist platform.

What sucks: Expensive if you're warming up multiple accounts—$29 per account adds up fast. The Lemwarm Score can be inconsistent and doesn't always reflect real-world inbox placement. Setup takes longer than other tools.

Best for: Solo senders or small teams with 1-3 email accounts who want higher-quality warmup conversations. Worth considering if you're already using Lemlist for cold email.

Try Lemlist with built-in Lemwarm

Reply.io Warmup

Reply.io includes email warmup as part of its sales engagement platform. Plans start at $60/month and include warmup for connected mailboxes.

The warmup feature automatically sends and receives emails through Reply's network. It adjusts sending volume based on your account's age and current reputation. The platform provides deliverability analytics and alerts you to issues.

What's good: Solid warmup performance for both Gmail and Outlook accounts. Good integration with Reply's multichannel outreach features. The platform monitors blacklists and sender reputation automatically.

What sucks: More expensive than Smartlead or Instantly if you only care about cold email and warmup. The warmup settings are buried in the interface. You can't use the warmup without subscribing to the full platform.

Best for: Sales teams using Reply.io for multichannel outreach (email, calls, LinkedIn) who need reliable warmup included. Overkill if you just need basic email warmup.

Explore Reply.io's warmup features

What to Look for in Email Warmup Tools

Not all warmup tools are equal. Here's what matters:

Network size: Bigger warmup networks mean more diverse email providers. You want your warmup emails going to Gmail, Outlook, Yahoo, and smaller providers—not just Gmail to Gmail.

Customization: Can you control ramp-up speed, daily volume limits, and conversation topics? More control means you can match the warmup to your actual sending patterns.

Spam folder interaction: Good warmup tools automatically move messages out of spam and mark them important. This is critical for building positive reputation signals.

Monitoring and reporting: You need visibility into your sender reputation, deliverability scores, and any blacklist flags. Without monitoring, you don't know if the warmup is working.

Pricing model: Per-account pricing gets expensive fast if you're warming up multiple domains. Unlimited warmup included with cold email platforms is usually more cost-effective.

Do You Actually Need Email Warmup?

Yes, if you're doing any cold outreach at scale. Here's when warmup is non-negotiable:

New domains: Any domain less than 3 months old needs warmup before sending cold emails. Email providers don't trust brand new domains.

New email accounts: Even on established domains, new email accounts need gradual warmup. Going from 0 to 100 emails per day overnight kills your deliverability.

Low sending volume: If your domain typically sends 10 emails per day and you suddenly start sending 200, that's a red flag. Warmup helps you ramp up gradually.

After a break: If an account stopped sending email for weeks or months, you need to warm it back up before resuming high-volume outreach.

You probably don't need warmup if you're sending under 20 emails per day from an established account, or if you're only emailing people you already have relationships with. Warmup is specifically for cold outreach and high-volume sending.

How Long Does Email Warmup Take?

Plan for 2-4 weeks minimum before sending cold email campaigns. Most warmup tools start slowly—maybe 5-10 emails per day—and gradually increase over several weeks.

Newer domains need longer warmup periods. A brand new domain should warm up for at least 4 weeks before heavy cold outreach. Established domains with new accounts can often start sending in 2-3 weeks.

Don't rush it. Starting cold campaigns too early tanks your sender reputation and can take months to recover. The extra week or two of warmup is worth it.

Email Warmup vs Cold Email Software

Email warmup tools fall into two categories: standalone warmup services and integrated features in cold email platforms.

Standalone warmup tools like Lemwarm charge per account (usually $25-50/month per account). They focus exclusively on warmup with detailed customization and monitoring. These make sense if you're using a cold email platform that doesn't include warmup, or if you want more control over the warmup process.

Integrated warmup in platforms like Smartlead, Instantly, and Reply is included with your subscription and typically allows unlimited accounts. These are more cost-effective if you're warming up multiple accounts, but offer less customization.

For most businesses doing cold outreach, integrated warmup makes more sense. You get everything in one platform, unlimited warmup accounts, and lower total cost. Only go with standalone warmup if you need advanced features or you're committed to a cold email platform that doesn't include warmup.

If you're comparing cold email platforms overall, check out our guide to the best cold email software for a full breakdown of features and pricing.

Common Email Warmup Mistakes

Starting campaigns too early: The biggest mistake. Give warmup at least 2 weeks, preferably 4 for new domains. Your eagerness to start sending isn't worth destroying your deliverability.

Turning off warmup after starting campaigns: Keep warmup running continuously while you're doing cold outreach. It maintains your sender reputation even as you send campaigns.

Using the same warmup account for campaigns: Your warmup emails should come from the same accounts that send your campaigns, but don't send campaigns and warmup emails simultaneously from one account beyond the platform's recommended limits.

Ignoring authentication: SPF, DKIM, and DMARC records must be properly configured before warmup starts. Warmup can't fix missing email authentication.

Warming up too aggressively: Some tools let you ramp up very quickly. Resist the temptation. Slower, gradual warmup looks more natural and builds better reputation.

Which Email Warmup Tool Should You Use?

If you're running cold email campaigns and need warmup for multiple accounts: Use Smartlead or Instantly. Both include unlimited warmup with cold email tools starting under $40/month. Smartlead has better deliverability features; Instantly has a cleaner interface.

If you need warmup for 1-2 accounts and want standalone service: Consider Lemwarm at $29/month per account if you value natural-looking warmup conversations. Otherwise, you're better off with a full cold email platform that includes warmup.

If you're already using a cold email platform: Check if warmup is included. Most modern platforms (Smartlead, Instantly, Reply, Lemlist) include it. If your current platform doesn't offer warmup, that's a sign you should switch platforms rather than paying for separate warmup.

If you're just getting started with cold email: Go with a platform that bundles warmup, email verification, and campaign management. Smartlead offers the best value for unlimited accounts. Instantly is easier to learn if you're new to cold email.

Email warmup isn't optional for cold outreach. Factor it into your timeline and budget before launching campaigns. The tools that bundle warmup with cold email platforms offer the best combination of features and pricing for most businesses.