Email deliverability has never been more critical—yet studies show that nearly 20% of legitimate business emails never reach the inbox.
For sales teams, marketers, and founders relying on cold outreach, that's a huge opportunity slipping into spam folders.
The problem?
New domains and fresh email accounts don't have the reputation needed to bypass strict spam filters.
That's where AI-powered email warmup software comes in. These tools simulate natural sending patterns—like gradual volume increases, real opens, clicks, and replies—to help build trust with Gmail, Outlook, and other providers.
Over time, they strengthen your domain reputation, ensuring that your emails are delivered where they belong: the inbox.
In this guide, we'll break down the 6 best email warmup tools using AI assistance in 2025, their features, pricing, and how to choose the right one for your strategy.
What is Email Warmup Software?
Email warmup software is a tool that helps you gradually build the reputation of a new or inactive email account so your messages don't end up in the spam folder.
Think of it like "breaking in" a new pair of shoes—if you try to run a marathon on day one, you'll get blisters. The same goes for email. If you start blasting hundreds of cold emails from a fresh account, email providers like Gmail and Outlook will flag you as suspicious and push your messages to spam.
Warmup software uses AI-driven simulations to send small batches of emails, generate real-looking opens, clicks, and replies, and slowly increase sending volume over time. This tells providers, "Hey, this is a trusted sender," which improves your deliverability and helps your future campaigns land in the inbox.
In short: email warmup software builds trust with email providers before you scale your outreach.
Email Warmup Tools Comparison Table (2025)
| Tool | Key features | Best For | Starting Price |
| Instantly | AI-powered engagement simulation, built-in spam testing, SMTP integration | Agencies & sales teams | $37.9/month |
| Warmup Inbox | Supports unlimited email accounts, simple setup, automated engagement | Freelancers & small businesses | $15/month |
| Mailwarm | AI warmup for Gmail & Outlook, gradual volume increase, daily reports | Professionals using G Suite/Outlook | $69/month |
| InboxAlly | Adjustable engagement pace, inbox placement tracking, real interaction network | Marketers scaling campaigns | $149/month |
| Quickmail | Works with SMTP/IMAP, flexible warmup across providers, affordable starter plan | Budget-conscious users & startups | $9/month |
| Folderly | Enterprise-grade warmup, domain health checks, blacklist monitoring | Enterprises & large teams | $96/month |
Why is Email Warmup Important?
Email warmup is a crucial step in any cold email outreach strategy.
By properly "warming up" your email account, you significantly improve the chances of your messages landing in the inbox instead of getting lost in the spam folder.
Here's the problem: not all emails are created equal. While many people use email for business or personal communication, others abuse it for spamming or malicious activity.
Because of this, Email Service Providers (ESPs) and Internet Service Providers (ISPs) carefully evaluate every sender's reputation before allowing large volumes of messages through.
If your account doesn't have a strong sending history, your emails are more likely to be filtered or blocked. That's where email warmup comes in.
By gradually increasing send volume and generating authentic engagement (like opens, clicks, and replies), warmup software helps build a positive reputation with ESPs and ISPs.
So in a nutshell it important for the following reasons:
Over time, this creates the trust you need to ensure your outreach consistently reaches your audience.
6 Best AI-driven email warmup tools you should consider.
#1. Instantly
If you're serious about cold email deliverability, Instantly stands out as one of the most complete warmup solutions. Unlike tools that only mimic basic email activity, Instantly combines AI-powered engagement simulation with built-in spam testing, giving teams a big edge in their outreach.
Cold email marketers know the pain: manual warm-ups are tedious and slow, while low-quality automation can trigger spam filters.
Instantly solves this by creating realistic human-like activity, helping your emails reach the inbox faster and more reliably—all for $37.9/month.
Key Features of Instantly
- AI-powered engagement simulation for natural warmup behavior.
- Pre-send spam testing against 30+ spam filters to avoid blacklisting.
- Multi-inbox warmup, great for agencies scaling multiple accounts.
- Real-time deliverability analytics with alerts for reputation drops.
- Integrations with HubSpot, Salesforce, and Zapier.
Pros:
- Highly scalable, ideal for agencies.
- Built-in spam filter testing.
- Unlimited inbox warmup support.
Cons:
- More advanced than freelancers or solo senders might need.
Pricing: Starts at $37.9/month.
#2. Warmup Inbox
Warmup Inbox is one of the most affordable warmup tools on the market, with plans starting at just $15/month.
What makes it stand out is the ability to warm up unlimited email accounts, making it an excellent fit for freelancers or startups looking for budget-friendly options.
Key Features of Warmup Inbox
- Supports unlimited inboxes for one flat fee.
- Automates inbox interactions like opens, replies, and clicks.
- Easy setup with SMTP/IMAP integration.
- Simple reporting dashboard for monitoring progress.
Pros:
- Very affordable.
- Unlimited account support at all price points.
- Easy to set up for beginners.
Cons:
- Fewer advanced deliverability insights compared to higher-end tools.
- Limited integrations with CRM or sales platforms.
Pricing: Starts at $15/month.
#3. Mailwarm
Mailwarm is designed specifically for Gmail and Outlook users who want a straightforward but powerful warmup solution.
Priced at $69/month, it's more expensive than some competitors but offers a focused, hands-off approach for professionals using mainstream providers.
Key Features of Mailwarm
- AI warmup for Gmail and Outlook accounts.
- Gradual send volume increases to protect domain reputation.
- Automated reply generation for authentic engagement.
- Daily warmup reports with performance insights.
Pros:
- Excellent choice for G Suite and Outlook users.
- Detailed reports for easy monitoring.
- Strong reputation for reliability.
Cons:
- Higher cost compared to Warmup Inbox or Quickmail.
- Limited to Gmail and Outlook ecosystems.
Pricing: Starts at $69/month.
#4. InboxAlly
InboxAlly positions itself as a premium warmup solution, with a price tag of $149/month.
What sets it apart is its ability to let you adjust the pace of engagement, giving you more control over how aggressively you warm up your accounts.
Key Features of InboxAlly
- Adjustable engagement pace for different strategies.
- Real inbox placement testing across major providers.
- Large warmup network simulating authentic opens and replies.
- Detailed sender reputation insights.
Pros:
- Highly customizable warmup strategy.
- Great analytics for inbox placement.
- Suitable for advanced marketers.
Cons:
- Expensive compared to other tools.
- Overkill for smaller teams or freelancers.
Pricing: Starts at $149/month.
#5. Quickmail
Quickmail is the most budget-friendly option, starting at just $9/month.
It's lightweight but effective, working with both SMTP and IMAP providers, making it accessible for startups or users testing email warmup for the first time.
Key Features of Quickmail
- Works with both SMTP and IMAP accounts.
- Automates warmup with realistic opens and replies.
- Simple to set up, beginner-friendly.
- Supports small-scale outreach alongside warmup.
Pros:
- Extremely affordable.
- Easy to use with a simple interface.
- Flexible account compatibility.
Cons:
- Limited analytics and advanced features.
- Not ideal for scaling agencies.
Pricing: Starts at $9/month.
#6. Folderly
Folderly is an enterprise-grade email warmup and deliverability platform priced from $96/month.
Unlike basic warmup tools, Folderly also includes domain health monitoring, blacklist detection, and advanced consulting, making it a full-service solution for larger businesses.
Key Features of Folderly
- AI-powered warmup combined with domain health checks.
- Blacklist monitoring to protect sending reputation.
- Spam filter diagnostics and resolution guidance.
- Tailored deliverability consulting for enterprise clients.
Pros:
- Comprehensive deliverability platform, not just warmup.
- Great for businesses sending at scale.
- Advanced blacklist and domain protection.
Cons:
- Higher price point compared to most tools.
- Too advanced for freelancers or very small teams.
Pricing: Starts at $96/month.
How to Incorporate Warmup Tools Into Your Strategy
Warming up your email account isn't just about flipping a switch and hoping for the best. To get the full benefit of warmup tools, you need to weave them into your broader outreach strategy.
Here's a step-by-step approach to doing it right:
1. Start with the Basics: Set Up Proper Authentication
Before you even think about hitting "send" on your cold emails or launching a warmup tool, you need to make sure your email infrastructure is set up correctly.
This step is often overlooked, but it's the foundation of email deliverability.
If your authentication isn't in place, email providers like Gmail, Outlook, and Yahoo will be quick to mark your messages as suspicious—no matter how advanced your warmup tool is.
Here are the three core records you should configure:
- SPF (Sender Policy Framework) - Think of SPF as your email account's security guard. It tells receiving servers which IP addresses or services are authorized to send emails on behalf of your domain. If your emails come from an unauthorized server, they're more likely to be flagged as spam.
- DKIM (DomainKeys Identified Mail) - DKIM is like a digital signature attached to each email you send. It verifies that your message hasn't been altered in transit and proves that it's genuinely coming from your domain. This adds another layer of trust in the eyes of ESPs and ISPs.
- DMARC (Domain-based Message Authentication, Reporting & Conformance) - DMARC builds on SPF and DKIM by giving email providers instructions on what to do if an email fails authentication checks. For example, you can set it to "monitor," "quarantine," or "reject" suspicious messages. This is crucial for preventing spoofing and phishing attacks that could damage your domain's reputation.
Without these protocols, you're essentially sending emails naked—providers can't verify that you're a trusted sender. And once your domain develops a poor reputation, it's much harder (and slower) to recover.
After setting up these records, use a testing tool (like MXToolbox, Google Postmaster Tools, or your warmup software's built-in checker) to confirm everything is configured properly.
By securing your email infrastructure with SPF, DKIM, and DMARC before starting warmup, you're giving your campaigns the strongest possible foundation for long-term deliverability success.
2. Begin Slowly and Build Up Volume Gradually
A new email account sending hundreds of cold emails on day one is a red flag. Instead, let the warmup tool start small—maybe 5–10 emails per day.
Over the course of 2–4 weeks, the tool will automatically increase the volume while simulating human-like engagement (opens, clicks, replies).
This signals to Gmail, Outlook, and others that your account is safe and trustworthy.
3. Align Warmup with Your Real Outreach
Don't treat warmup as an isolated process.
The goal is to merge it with your actual sending strategy.
For example:
- Use warmup alongside your real prospecting campaigns.
- Stagger cold outreach so it doesn't spike suddenly after warmup.
- Continue partial warmup in the background even after you start real campaigns, to keep your reputation strong.
4. Monitor Deliverability Reports and Adjust
Most warmup tools give you daily or weekly reports showing inbox placement, spam score, and engagement levels.
Use these insights to make adjustments:
- If deliverability drops, pause or slow your campaigns.
- Fix any DNS issues flagged in the reports.
- Rotate or rest accounts if one gets flagged too often.
5. Scale Safely Across Multiple Accounts and Domains
If you're planning to run cold outreach or nurture campaigns at scale, one of the biggest mistakes you can make is to rely on a single email account or even a single domain.
Doing so puts all your eggs in one basket—if that account gets flagged or throttled, your entire campaign grinds to a halt.
Instead, smart teams use a multi-account, multi-domain strategy to spread out the sending volume and reduce risk.
Here's how it works in practice:
- Warm up multiple inboxes in parallel - Don't just warm up your main account. Create additional inboxes (for example, from subdomains or secondary domains) and run them through the warmup process too. This gives you a pool of "ready" accounts to rotate through.
- Rotate sending across accounts - Instead of sending 1,000 emails from one inbox in a single day, you could send 200 each from five different accounts. The total volume is the same, but the burden on each account is lower—keeping your reputation strong.
- Use subdomains strategically - Subdomains (e.g., outreach.yourdomain.com or sales.yourdomain.com) can be warmed up separately from your primary corporate domain. This way, even if your outreach subdomain runs into deliverability issues, your main domain stays unaffected.
- Balance your sending volume - Warmup tools can help you slowly increase the daily limits for each account, but you should still distribute volume intelligently. Avoid sudden spikes or dumping all your outreach on one inbox just because it's performing well.
- Maintain backups - Even with careful planning, things can go wrong—an account may get temporarily suspended, blacklisted, or flagged. Having multiple warmed accounts ensures you always have a backup ready to step in, so campaigns keep moving without interruption.
Some AI warmup platforms let you manage multiple inboxes under one dashboard, making it easier to monitor deliverability, rotate accounts, and spot issues early.
This is particularly useful for agencies or sales teams running high-volume campaigns across multiple clients or markets.
By scaling safely with multiple accounts and domains, you protect yourself from single points of failure, build resilience into your email strategy, and ensure consistent results—even if one account temporarily struggles.
6. Keep Warming—Even After You Launch
Email warmup isn't a one-and-done process.
Even established accounts can get flagged if you suddenly increase sending volume or get too many negative signals (like spam complaints).
Keep your warmup tool running in the background to maintain consistent engagement and protect your sender reputation over time.
Common Mistakes to Avoid When Warming Up Emails
Even with the right software, many senders still make mistakes that hurt their deliverability.
Avoid these pitfalls to get the best results from your warmup process:
- Sending Too Many Emails Too Quickly - One of the fastest ways to raise red flags with email providers is by blasting out a large volume of emails right away. A new or cold account should start small—just a handful of emails per day—and gradually scale up. Warmup tools are designed to automate this process, but if you override the limits, you risk being flagged as spam before you even get started.
- Using Newly Purchased Domains Without Aging - Freshly registered domains don't have any history, which makes them suspicious in the eyes of ESPs and ISPs. If you immediately start sending outreach campaigns from a brand-new domain, it's almost guaranteed to be flagged. The better approach is to let your domain "age" for a few weeks while running warmup sequences in the background to build credibility.
- Ignoring Deliverability Reports - Most warmup tools provide detailed insights into inbox placement, spam complaints, and engagement metrics. Ignoring these reports is like driving with your eyes closed—you won't notice problems until it's too late. Regularly review these analytics to catch early warning signs, adjust sending behavior, and fix DNS or reputation issues before they snowball.
- Forgetting to Align Warmup with Real Outreach - Warming up an inbox is only the first step. Too many senders treat warmup as a box to check and then immediately switch to aggressive cold campaigns. Instead, your actual outreach should mirror the warmup process—gradual increases, consistent engagement, and authentic messaging. If your real campaigns suddenly spike far above the levels established during warmup, your reputation can still take a hit.
Think of email warmup as training for a marathon. You wouldn't sprint on day one—you'd pace yourself, track your progress, and build up endurance.
Apply the same discipline to your email campaigns, and you'll enjoy consistent inbox placement and stronger engagement.
Conclusion
In 2025, AI-powered email warmup tools are no longer a nice-to-have—they're a necessity for anyone relying on cold outreach or high-volume email campaigns.
With inboxes getting smarter and filters becoming stricter, building and maintaining a strong sender reputation is the only way to consistently reach your audience.
Whether you're a freelancer looking for a simple, affordable option like Warmup Inbox, or an enterprise team that needs advanced monitoring with Folderly, the right tool can make all the difference.
By simulating real engagement, gradually scaling your volume, and protecting your domain reputation, warmup software gives your emails the credibility they need to land directly in the inbox.
The key is to start small: pick one tool, monitor your results, and then scale with confidence.
With the right warmup strategy in place, you'll not only avoid the spam folder but also see higher open rates, stronger engagement, and more meaningful conversations with your prospects.
Frequently Asked Questions About Email Warmup Software
1. What is email warmup software and why is it important for email deliverability?
Email warmup software is a tool that gradually builds trust between your email account and providers like Gmail or Outlook. By simulating real interactions—such as opens, clicks, and replies—it strengthens your sender reputation.
This process improves email deliverability, ensuring your cold outreach lands in the inbox instead of the spam folder.
2. How does AI-powered email warmup improve inbox placement?
AI-powered email warmup uses smart algorithms to mimic human behavior, such as engaging with your emails in realistic ways.
These actions help email service providers view your account as trustworthy, boosting your inbox placement rate and reducing the risk of being flagged as spam.
3. How long should I use email warmup tools for a new account?
The recommended warmup period for a new email account is typically 2–4 weeks. During this time, warmup tools gradually increase your sending volume and build a positive reputation.
The exact duration depends on your outreach goals, domain age, and desired daily sending limits.
4. Can I warm up multiple domains and email accounts at the same time?
Yes, most modern email warmup tools support multi-domain and multi-account warmup.
This is especially useful for agencies, sales teams, or businesses managing several campaigns at once.
Running parallel warmups helps distribute volume, reduce risk, and ensure consistent email deliverability across all accounts.
5. What's the difference between manual email warmup and AI-driven warmup software?
Manual email warmup requires you to send small batches of emails yourself, wait for replies, and slowly increase the volume.
This process is time-consuming and inconsistent.
In contrast, AI-driven warmup software automates the entire process—sending, replying, and engaging with emails in a natural way.
The result is faster, more reliable, and more effective deliverability improvement.