Best Email Warmup Tools to Keep You Out of Spam

by Maildoso's team

05/28/2025

difficulty level ⭐⭐

If you’re sending cold emails or running outreach campaigns, you’ve probably heard how important it is to “warm up” your email account first. But what does that actually mean? Email warmup is the process of gradually building your sender reputation so email providers trust your account. Without it, your emails might end up in the spam folder or, worse, get blocked altogether. That’s why email warmup tools are a game changer - they help you ease into sending emails without raising red flags with services like Gmail or Outlook.

These tools do the heavy lifting for you by simulating real conversations, slowly increasing your send volume, and improving your sender score. Whether you’re a solo founder launching a newsletter or part of a sales team sending hundreds of cold pitches, the right warmup tool can make all the difference. In this article, we’ll break down the best email warmup tools available today, explain how they work, and help you choose one that fits your goals.

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1. Maildoso

At Maildoso, we’ve built a cold email infrastructure designed to help teams send high volumes of emails while maintaining strong deliverability. Our platform takes care of the complex technical setup - like configuring SPF, MX, and DKIM records - so you don’t have to. Whether you're setting up a few mailboxes or scaling to hundreds, we make it possible to get everything running in just minutes instead of days.

Our AI-powered warmup tool sets us apart. Instead of using traditional IMAP-based systems that email providers often flag, we use browser-based AI agents that simulate real user behavior. These agents perform in-browser actions and send up to 100 emails per day per mailbox. The result is a warmup process that feels more authentic to email providers, reducing spam complaints and boosting your inbox placement.

We also handle the behind-the-scenes infrastructure to keep your campaigns running smoothly. If one of our IPs encounters an issue, we rotate it automatically without any disruption to your outreach. This helps maintain a consistent deliverability rate, even when you're sending tens of thousands of emails daily. You stay focused on your campaigns - we’ll take care of the technical part.

To make life easier, we include domains with every mailbox, and you own them even if you cancel your plan. Our out-of-the-box setup includes domain forwarding and a master inbox, letting you centralize responses from multiple mailboxes. We’re here to save you time, reduce stress, and give you the tools to scale outbound emails with confidence.

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2. Instantly

Instantly is a sales engagement platform designed to improve email deliverability through a fully automated network. The platform uses a large pool of over one million real email accounts to simulate positive interactions, which helps enhance sending reputation and avoid spam filters. After connecting their email accounts, users can activate the deliverability boost with a single click, simplifying the process of warming up email addresses.

A deliverability dashboard is available to monitor inbox and spam rates, offering clear insights into when email accounts are ready for outreach. Instantly also allows users to customize warmup behavior by adjusting open and reply rates, daily volume, and enabling features like read emulation. These settings help create realistic sending patterns that support more effective outreach efforts.

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3. Warmup Inbox

Warmup Inbox is a deliverability-focused tool that automates the process of warming up email accounts to improve inbox placement. The platform simulates natural email interactions - such as sending, opening, replying to, and marking messages as important - by connecting real user inboxes within its network. This helps email accounts build a positive sender reputation and reduces the chances of messages being flagged as spam or diverted to promotional folders.

In addition to its warmup functionality, Warmup Inbox provides users with a Reputation Score that measures their current sender status and compares it against community benchmarks. The platform sends alerts when reputation drops, allowing users to pause their campaigns before further issues arise. Designed for ease of use, the tool supports integrations with various inbox types via API and does not rely on fake or disposable email accounts.

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4. Emailwarmup.com

Emailwarmup.com offers a service focused on improving email deliverability by helping emails avoid spam folders and land in recipients’ inboxes. The platform supports integration with Gmail, Outlook, and other email platforms, enabling users to connect their accounts quickly and begin the warmup process within seconds. This process aims to simulate normal email activity to build a positive sender reputation, which is especially useful for teams running cold outreach or email marketing campaigns.

The platform also provides users with tools to monitor email health and deliverability in real-time. With visibility across a team’s email performance and inbox placement, companies can identify and address deliverability issues before they impact outreach efforts. The service includes customizable warmup settings tailored to a user's specific newsletter or automation flows, as well as access to email deliverability consultants who can assist with strategy and setup.

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5. Snov.io

Snov.io offers an email warm-up tool designed to help users improve their email deliverability and maintain a solid sender reputation. The platform addresses common issues with cold outreach, such as messages landing in spam or promotions folders, by automatically managing warm-up activities across supported email providers. With features like AI-powered conversations and customizable strategies, Snov.io aims to ensure emails consistently reach primary inboxes, enhancing the chances of engagement.

The warm-up process includes sending realistic, same-thread conversations to simulate natural email behavior, which helps build trust with email service providers. Users can personalize strategies depending on their needs - whether they're preparing a new domain, recovering a damaged reputation, or improving inbox placement. The tool also offers analytics through a dashboard that provides real-time updates on deliverability and performance by provider. Snov.io supports integration with multiple email services and provides additional tools for outreach, email verification, and lead generation.

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6. Lemlist

Lemlist is a platform that focuses on improving cold email outreach by helping businesses increase their email deliverability and avoid spam folders. Its core offering includes lemwarm, a deliverability and inbox placement tool designed to warm up email addresses by gradually sending messages to a trusted network. This process enhances sender reputation and boosts domain credibility, improving the chances of emails landing in a prospect’s primary inbox rather than being flagged as spam.

lemwarm operates on autopilot, sending emails in a human-like pattern to a premium network. It also continuously monitors the deliverability score, sending volume, and potential spam triggers, alerting users to risks in real time. Users on paid lemlist plans like Email Pro, Multichannel Expert, or Outreach Scale receive lemwarm access on the Essential plan, while upgrades to the Smart plan include a $29 monthly discount per seat. Case studies provided by the platform show measurable improvements in open rates, meeting bookings, and revenue when switching from lower deliverability setups to those supported by lemwarm.

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7. Smartlead.ai

Smartlead.ai is a cold email automation platform that emphasizes email warmup to improve inbox placement and deliverability. The company provides tools designed to help businesses avoid spam folders and maintain a strong sender reputation when conducting outreach campaigns. With an AI-powered system, Smartlead.ai focuses on mimicking human conversation patterns during the warmup process, enabling users to scale outreach without compromising their email reputation.

The platform supports warming up multiple email accounts simultaneously and includes automatic adjustments to match mailbox providers and handle MX record configurations. Smartlead.ai offers features such as spintax support, rotating inboxes, tagging, subsequences, and white labeling. The system also includes a unified master inbox and mobile app for managing outreach activity. According to customer testimonials featured on the website, the tool is known for being user-friendly and supported by a responsive team.

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8. Mailivery

Mailivery is an email deliverability tool designed to improve sender reputation and increase the chances of landing in the primary inbox instead of the spam or promotions folders. The platform uses AI-driven email interactions to simulate genuine engagement. These interactions include opening emails, removing them from spam, and generating positive replies - all of which help build a more trustworthy sender profile over time.

The system is built for scalability and team use, offering management tools for larger sales teams and high-volume senders. Users can monitor detailed deliverability analytics in real time and check if their domains or IP addresses are blacklisted. Mailivery provides customizable warm-up settings, allowing control over the volume and frequency of email interactions to align with user-specific needs.

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9. Mailwarm

Mailwarm is a deliverability-focused tool designed to improve the chances of emails reaching recipients' inboxes, especially for businesses running cold outreach campaigns. The platform works by simulating organic email interactions using a network of over 1,000 email accounts. These accounts exchange emails with the user's connected address, performing actions like opening, replying to, and marking messages as important - activities that positively influence sender reputation.

The tool is built to help maintain consistent email activity from both quantitative and qualitative perspectives. Mailwarm operates on a daily schedule set by the user, allowing them to gradually raise their domain, email, and IP reputation. A dashboard is available to track and manage interactions, adjust the intensity of the warm-up process, and pause the service if needed. The overall goal is to support long-term email deliverability for users running outreach campaigns.

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10. MailToaster

MailToaster is an automated email warm-up platform designed to improve deliverability for outbound email campaigns. The tool works by gradually building and maintaining a sender’s reputation through realistic email interactions. This process includes sending and receiving messages across a trusted network of real inboxes, ensuring that accounts avoid spam folders and blacklists. Users can connect email accounts from providers like Gmail, Outlook, or others and begin the warm-up process without requiring any technical knowledge.

The service offers multiple warm-up profiles tailored to specific needs, such as new account ramp-up or maintaining reputation on older accounts. It simulates positive engagement - opening emails, replying, removing them from spam, and marking them as important. MailToaster also provides DNS validation tools to check SPF, DKIM, and DMARC records, helping users ensure proper email configuration. Progress can be monitored through detailed reports. The platform is priced at $29 per email account per month, with a 7-day free trial available.

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11. TrulyInbox

TrulyInbox is an email warm-up platform designed to enhance email deliverability by simulating authentic email interactions. By gradually increasing email sending volumes and engaging in realistic behaviors such as opening, replying, and marking emails as important, TrulyInbox aims to improve sender reputation and reduce the likelihood of emails being marked as spam. The platform supports integration with various email service providers, including Gmail, Outlook, Yahoo Mail, Zoho, GoDaddy, and Yandex .

The service offers customizable warm-up schedules, allowing users to adjust the number of emails sent daily, set reply rates, and monitor deliverability scores through a reporting dashboard. Security measures include AES-256 encryption for data at rest and TLS 1.2/1.3 protocols for data in transit. User credentials are hashed and salted using bcrypt, and multi-factor authentication is available .

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12. MailReach

MailReach is an email deliverability platform that focuses on improving sender reputation through automated warm-up processes and spam testing. It operates by initiating interactions with a network of high-reputation inboxes, simulating natural email behaviors such as opens, replies, and moving messages out of spam folders. This approach aims to enhance the likelihood of emails reaching recipients' primary inboxes .

The platform is compatible with various email service providers that support SMTP, including Gmail, Outlook, SendGrid, Mailgun, and Amazon SES. Users can monitor their email performance through a dashboard that provides insights into sender scores, inbox placement, and spam rates. MailReach also offers tools for spam testing and reputation monitoring to help users maintain optimal email deliverability .

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13. Folderly

Folderly is an email deliverability platform that offers tools to enhance the success of email campaigns. It provides features such as email warm-up, spam testing, and deliverability monitoring to help users improve their sender reputation and ensure emails reach recipients' inboxes.

The platform includes services like Inbox Insights for analyzing email placement and DNS settings, and Pulse for real-time monitoring of spam placement. Folderly also offers a spam words checker to identify and remove potential spam triggers in email content, aiming to improve overall email performance.

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Conclusion

If you’re serious about getting your emails seen - and not buried in the spam folder - email warmup tools are a smart investment. Whether you're launching a brand-new account or trying to maintain deliverability on an existing one, these tools can make a big difference by building your sender reputation gradually and safely.

The good news is that there are several solid options out there, each with its own features and pricing to match different needs. From automated warm-up sequences to tools that mimic real engagement, you’ve got plenty of ways to improve your email performance. At the end of the day, consistent warmup is one of the easiest ways to give your outreach campaigns the best shot at success.

Double your outbound sales with Maildoso!

We provide the infrastructure for cold outreach with the highest possible deliverability. Forget about the spam folder—set up hundreds of mailboxes in just 10 minutes, starting at only $1.80/month!

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