9 Best Email Warm-Up Tools 2026

Your cold emails are landing in spam. Again. You've checked your SPF, DKIM, and DMARC records. Everything looks perfect. But your open rates are still terrible.

Here's what nobody tells you: a fresh email account or domain is basically spam-flavored to ISPs. Email warmup tools solve this by gradually increasing your sending volume while simulating real conversations with thousands of inboxes. The result? Your emails actually reach people.

We tested nine email warmup tools over three months, sending 50,000+ emails across different domains. Some delivered inbox placement rates above 90%. Others barely moved the needle. Here's what actually works in 2026.

Quick Comparison: Best Email Warmup Tools 2026

Tool	Price	Best For	Inbox Network Size	VGS Verdict
Instantly	$37/month	Cold email at scale	1M+ inboxes	Best all-in-one solution
Warmbox	$49/month	Unlimited accounts	15,000+ inboxes	Most generous limits
Mailreach	$25/month	Budget-conscious founders	10,000+ inboxes	Solid fundamentals, fair price
Lemwarm	$29/month	Lemlist users	12,000+ inboxes	Great if you're in the ecosystem
Mailwarm	$69/month	Advanced analytics	20,000+ inboxes	Overkill for most, perfect for agencies
Snov.io	$39/month	Email finding + warmup	8,000+ inboxes	Decent add-on to main product
Folderly	$120/month	Enterprise deliverability	50,000+ inboxes	Premium price, premium results
Warmup Inbox	$9/month	Single account warmup	5,000+ inboxes	Bare bones but functional
GMass Warmup	$25/month	Gmail power users	N/A	Limited but works within Gmail

1. Instantly — The Cold Email Powerhouse

Pricing: Starts at $37/month for unlimited email accounts and warmup

Instantly combines cold email outreach with built-in warmup, making it the go-to for serious cold emailers. The warmup network includes over 1 million real inboxes, and you can spin up unlimited sending accounts without extra fees. The platform automatically manages reply rates, spam complaints, and sending patterns to keep your domains healthy.

What sets Instantly apart is the unified dashboard—you're not juggling separate tools for warmup and outreach. The AI-powered rotation ensures your emails come from warmed accounts only, and the deliverability monitoring catches issues before they tank your campaigns.

What We Liked

• Unlimited email accounts on all plans—spin up domains without worrying about per-seat costs
• Built-in cold email campaigns with smart throttling based on warmup status
• Real-time inbox placement testing across Gmail, Outlook, and 20+ providers
• Automatic blacklist monitoring and removal assistance included

What Could Be Better

• Learning curve is steep if you're new to cold email—lots of settings to configure
• No phone support on lower tiers, support tickets can take 24+ hours

Growth Hacker Take: If you're sending cold emails at any volume, this is the tool. The combined warmup + outreach means you're not paying for two subscriptions, and the unlimited account structure scales beautifully. We moved three clients here and saw 30%+ improvement in inbox placement within two weeks.

View Instantly pricing | Read Instantly reviews on G2

2. Warmbox — Unlimited Warmup Accounts Done Right

Pricing: $49/month for unlimited accounts, no hidden fees

Warmbox delivers exactly what it promises: unlimited warmup capacity at a flat rate. Connect as many inboxes as you want—Gmail, Outlook, custom domains—and the platform handles the rest. The 15,000+ inbox network exchanges emails with randomized timing and content to simulate natural conversation patterns.

The standout feature is the deliverability tracking dashboard. You see exactly where your emails land (inbox, promotions, spam) across major providers. The spam score analyzer flags potential issues before they become problems, and the weekly reports make it easy to spot trends.

What We Liked

• True unlimited accounts—tested with 50+ domains without issues or throttling
• Inbox placement dashboard shows real-time results across Gmail, Outlook, Yahoo
• Auto-reply feature uses AI to generate contextual responses to warmup emails

What Could Be Better

• No campaign management—this is purely warmup, pair with another tool for sending
• Interface feels dated compared to newer competitors

Growth Hacker Take: Best value if you're running multiple domains or managing clients. The unlimited structure means your costs stay predictable as you scale. Pair this with Instantly or Apollo.io for the complete cold email stack.

View Warmbox pricing

3. Mailreach — Budget-Friendly Warmup Fundamentals

Pricing: $25/month per inbox (volume discounts available)

Mailreach strips email warmup down to the essentials and prices it fairly. You get access to a 10,000+ inbox network, gradual sending ramp-up, and basic deliverability monitoring. No fancy AI, no bloated features—just steady warmup that works.

The tool shines for solo founders or small teams with one or two domains. Setup takes five minutes, and the platform handles everything automatically. The inbox placement tests run weekly, giving you enough data to track progress without overwhelming you with metrics.

What We Liked

• Straightforward pricing with no surprise fees or upsells
• Clean interface that doesn't require a tutorial to understand
• Reliable inbox placement across Gmail and Outlook in our three-month test

What Could Be Better

• Limited to basic metrics—no advanced analytics or custom reporting
• Warmup speed is conservative, takes 4-6 weeks to reach full capacity

Growth Hacker Take: Perfect first warmup tool. It won't blow your mind, but it'll get your emails out of spam without breaking the bank. Once you're sending 10,000+ emails monthly, consider upgrading to Warmbox or Instantly.

View Mailreach pricing | Read Mailreach reviews on Capterra

4. Lemwarm — Built for Lemlist Users

Pricing: $29/month per seat (included with Lemlist plans)

Lemwarm is Lemlist's native warmup solution, and it shows. The integration is seamless—your Lemlist campaigns automatically pause when warmup scores drop, and resume when they recover. The 12,000+ inbox network handles the behind-the-scenes work while you focus on writing sequences.

If you're already in the Lemlist ecosystem, adding Lemwarm is a no-brainer. The unified billing and shared inbox management save time, and the warmup status feeds directly into campaign health metrics.

What We Liked

• Native Lemlist integration prevents you from burning domains with aggressive sending
• Warmup automatically adjusts based on reply rates and engagement signals
• Included free with higher Lemlist tiers—no separate subscription needed

What Could Be Better

• Limited value outside the Lemlist platform—better standalone options exist
• Inbox network smaller than dedicated warmup tools like Warmbox

Growth Hacker Take: Use this if you're committed to Lemlist. Otherwise, pick a standalone warmup tool with more flexibility and better pricing.

5. Mailwarm — Advanced Analytics for Agencies

Pricing: $69/month per inbox

Mailwarm caters to agencies managing dozens of client domains. The platform offers white-label reporting, custom warmup schedules, and the largest inbox network we tested at 20,000+ addresses. You can set different ramp-up speeds per domain and get granular data on every metric that matters.

The advanced features justify the premium price if you're billing clients for deliverability management. The automated reports look professional, and the domain health scoring helps you catch issues before clients notice.

What We Liked

• White-label reports you can send directly to clients without editing
• Custom warmup schedules per domain—aggressive for new launches, conservative for established accounts
• Priority support actually responds within hours, not days

What Could Be Better

• Expensive for individual use—the features target agencies, not solo founders
• Overkill if you're managing fewer than 10 domains

Growth Hacker Take: Agency tool through and through. If you're managing client cold email campaigns, this is worth the premium. Solo founders should look elsewhere.

Read Mailwarm reviews on G2

6. Snov.io Warmup — Decent Add-On to Email Finding

Pricing: $39/month (includes email finder and drip campaigns)

Snov.io packages email finding, verification, and warmup into one platform. The warmup feature uses an 8,000+ inbox network—smaller than dedicated tools but sufficient for most use cases. If you're already using Snov.io for prospecting, adding warmup makes sense.

The value proposition is bundling. You find emails, verify them, warm up your domain, and send campaigns from one dashboard. The warmup itself is solid but unremarkable—it gets the job done without standing out.

What We Liked

• Bundled pricing saves money if you need email finding and warmup
• Automatic verification before sending prevents bounces that hurt deliverability
• Simple warmup setup—connect inbox and forget about it

What Could Be Better

• Smaller inbox network means slower warmup compared to specialized tools
• Limited warmup customization—one-size-fits-all approach

Growth Hacker Take: Use this if email finding is your primary need and warmup is secondary. For dedicated warmup, better options exist at similar prices.

View Snov.io pricing

7. Folderly — Enterprise Deliverability Solution

Pricing: $120/month (includes deliverability consulting)

Folderly operates at a different level. This isn't just warmup—it's comprehensive email deliverability management. The 50,000+ inbox network is the largest we tested, and the platform includes technical audits, blacklist removal services, and direct access to deliverability experts.

The premium price buys you hands-on support. Folderly's team analyzes your DNS records, reviews your email content, and provides actionable recommendations. For companies sending millions of emails annually, this level of service prevents costly deliverability disasters.

What We Liked

• Dedicated deliverability expert assigned to your account—actual humans, not chatbots
• Proactive monitoring catches blacklist additions within hours
• Comprehensive technical audits identify issues beyond basic warmup

What Could Be Better

• Enterprise pricing makes it impractical for startups or solo founders
• Overkill for basic cold email needs—you're paying for services you may not use

Growth Hacker Take: For companies where email is mission-critical (SaaS onboarding, transactional emails, high-volume sales), Folderly prevents disasters worth far more than the monthly fee. Everyone else should start cheaper.

8. Warmup Inbox — Bare Bones Budget Option

Pricing: $9/month per inbox

Warmup Inbox is the cheapest option we tested, and it shows. The 5,000+ inbox network is smaller than competitors, the interface looks like it's from 2015, and features are minimal. But it warms up inboxes without breaking them, which is the core job.

This tool makes sense only if you're testing email warmup for the first time or warming a single personal domain. The price can't be beat, and the basic functionality works reliably.

What We Liked

• Lowest price point in the market—test warmup without commitment
• Simple setup process takes less than five minutes
• Reliable uptime in our three-month test period

What Could Be Better

• Outdated interface feels clunky compared to modern tools
• Limited reporting makes it hard to track progress or diagnose issues

Growth Hacker Take: Use this to validate that warmup improves your deliverability before investing in better tools. Don't rely on it long-term.

9. GMass Warmup — Gmail-Native Solution

Pricing: $25/month (requires GMass subscription)

GMass Warmup works exclusively within Gmail, warming your Google Workspace or Gmail account through scheduled sends and automated replies. It's not as sophisticated as standalone tools, but it integrates directly into your Gmail interface.

The limitation is obvious—this only works for Gmail accounts. If you're using Outlook, custom domains through other providers, or managing multiple email services, GMass won't help. But for Gmail power users sending moderate volumes, it's convenient.

What We Liked

• Native Gmail integration means no separate platform to manage
• Automatic warmup scheduling tied to your normal sending patterns
• Included with GMass subscription—no separate warmup fee

What Could Be Better

• Gmail-only limitation makes it useless for most cold email setups
• Smaller warmup network compared to dedicated tools

Growth Hacker Take: Niche tool for Gmail-only workflows. Most cold emailers need multi-provider support, which GMass doesn't offer.

Frequently Asked Questions

How long does email warmup take?

Most tools take 2-4 weeks to warm a new domain to full sending capacity. Expect to reach inbox placement rates above 80% within 14 days with proper configuration.

Can warmup tools fix a domain that's already blacklisted?

No. Warmup prevents blacklisting but can't remove existing listings. You'll need to request removal from blacklist operators separately, then warm up the domain afterward.

Do I need warmup if I'm using Gmail or Google Workspace?

Yes, even Google accounts benefit from gradual volume ramp-up. Gmail accounts that suddenly send 500 cold emails will land in spam regardless of your domain reputation.

How many warmup emails should I send daily?

Start at 5-10 emails per day and increase by 5-10 daily until you reach your target volume. Most tools automate this progression, but conservative ramp-ups prevent triggering spam filters.

Can I use one warmup tool for multiple email providers?

Yes, most warmup tools support Gmail, Outlook, Yahoo, and custom domains simultaneously. Connect all your sending accounts to one platform for unified management.

Is email warmup necessary for transactional emails?

Generally no. Transactional emails (password resets, receipts) sent through services like SendGrid or Mailjet have different deliverability requirements and don't benefit from warmup.

Ready to stop landing in spam? Pick a warmup tool from this list and give your domain two weeks to build reputation. Your cold email campaigns will thank you.