Best Email Warm Up Tools to Improve Your Inbox Placement

by Maildoso's team

05/20/2025

difficulty level ⭐⭐

Before sending cold outreach or launching a new domain for email marketing, it's important to warm up your mailbox. Without proper warm-up, emails often land in spam or go undelivered. That’s where email warm up tools come in. These platforms simulate real human activity to help build sender reputation, improve deliverability, and ensure your messages reach real inboxes. In this article, we’ll look at some of the best email warm up tools available, covering their key features and how they support successful email campaigns.

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1. Maildoso

We are Maildoso, a cold email infrastructure platform built to help B2B teams scale outreach without technical friction. Our system automates the setup of domains and mailboxes, removing the need for manual DNS edits or third-party service providers. All mailboxes come pre-configured and optimized for cold outreach, allowing you to start sending in minutes. Because we’ve focused on reliable inbox preparation from the beginning, many teams rely on Maildoso as one of the best email warm up tools to prepare domains before launching outbound campaigns.

At Maildoso, we understand that deliverability is one of the biggest challenges in cold emailing. That’s why our platform includes IP rotation, domain warming, and built-in deliverability testing to help keep emails out of spam folders. We also use browser-based AI agents for warm-up - a method that simulates real inbox behavior to build trust with email providers. Whether you're managing five mailboxes or hundreds, the system is built to maintain steady, consistent sending without triggering filters.

To support long-term success, Maildoso includes practical tools and hands-on assistance at every stage of a campaign. You can request detailed audits covering spam triggers, copy structure, link usage, Spintax formatting, and unsubscribe compliance. We also help with custom tracking domain setup, centralized inbox management, and ongoing warm-up to protect domain reputation. In addition, we provide free learning resources and access to a private Slack community for peer collaboration and support.

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2. Saleshandy

Saleshandy is a cold email outreach platform that includes an automated warm-up feature aimed at improving email deliverability for new or inactive domains. The warm-up module simulates authentic user engagement by sending messages between trusted inboxes, opening them, and generating replies. This activity signals positive sender behavior to email service providers.

Users can track warm-up progress through a dashboard that displays metrics such as inbox placement rates, bounce rates, and email health scores. The system also flags potential issues like domain authentication problems or abnormal response patterns that may impact deliverability. Saleshandy supports multiple email providers, allowing businesses to warm up various accounts concurrently and maintain separate metrics for each inbox.

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3. Instantly.ai

Instantly.ai is a cold outreach and email warm-up tool that includes a built-in system for gradually improving inbox placement. It automates the warm-up process by sending messages between networked inboxes, which simulate authentic engagement behaviors such as opening, replying, and removing messages from spam. These actions help signal healthy activity to spam filters and email providers. 

Users can monitor email performance through dashboards that display inbox placement across various providers, engagement history, and sender health metrics. Instantly.ai also supports warm-up tracking for multiple domains and integrates with campaign modules, allowing for real-time performance adjustments. 

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4. Snov.io

Snov.io includes a warm-up feature as part of its broader email outreach system. The warm-up engine operates by sending a controlled number of messages between verified email accounts, creating artificial interactions such as replies and thread continuations. This helps reduce the risk of new email domains being flagged as suspicious by providers. 

The warm-up process is logged through a reporting interface that shows inbox placement rates, spam folder occurrences, and response patterns. Snov.io also validates the domain’s DNS records, ensuring that SPF, DKIM, and DMARC settings are correctly configured before initiating warm-up. 

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5. Lemwarm

Lemwarm is an automated warm-up tool originally developed as a standalone service and now integrated into Lemlist. It sends a sequence of emails between a large network of mailboxes and triggers actions like marking messages as important, replying, and removing from spam folders. These signals help build credibility for the sender's domain. 

A reporting module shows detailed breakdowns of where emails land - primary inbox, promotions, or spam - and tracks open and reply rates during the warm-up process. It also flags issues related to domain configuration or inconsistencies in delivery patterns. Lemwarm supports setup across Gmail, Outlook, and custom SMTP accounts, and is used to stabilize email infrastructure before launching outbound campaigns.

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6. Warmy.io

Warmy.io is a warm-up automation tool that simulates real email interactions to enhance sender reputation. It connects to mailboxes across multiple platforms and performs actions such as sending, opening, replying, and archiving emails to simulate human engagement. The system adapts to domain health by regulating daily email limits and gradually scaling the volume.

Users can view detailed deliverability scores, spam placement metrics, and reputation benchmarks through a visual dashboard. Warmy.io also evaluates the status of DNS records and monitors blacklist databases to detect any potential threats to delivery. The platform supports inboxes on Gmail, Outlook, and other major providers and includes customizable warm-up sequences to fit different outreach volumes.

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7. Mailreach

Mailreach is a deliverability optimization platform that automates email warm-up through a network of real inboxes. It sends emails that are opened, replied to, and marked as important, mimicking human interaction. This helps improve sender reputation across various providers. The warm-up volume increases gradually, starting from low send counts to avoid triggering spam filters.

The platform provides daily analytics showing inbox versus spam placement, bounce rates, and provider-specific reputation scores. It also scans DNS settings for issues in SPF, DKIM, and DMARC alignment. Mailreach supports managing warm-up for multiple inboxes simultaneously and is often used prior to launching cold email campaigns to ensure stability and reduce delivery errors.

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8. Lemlist

Lemlist is an outreach platform with a built-in warm-up tool that simulates engagement across its internal network. The system initiates gradual message exchanges between verified inboxes, with each message being opened and replied to in a human-like manner. This activity helps new domains build reputation and older domains maintain inbox trust.

The warm-up component displays deliverability metrics such as response rates, folder placement, and domain health. Lemlist allows users to configure daily email caps and track inbox performance for Gmail, Outlook, or custom servers. Users can transition directly from warming to live campaigns within the same interface, with historical data maintained for evaluation.

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9. GMass

GMass integrates warm-up functions tailored to Gmail-based outreach. It initiates automatic sending and receiving of internal test emails that are marked as opened and replied to. These interactions help Gmail identify the domain as trustworthy, particularly for new senders or domains that have experienced delivery issues.

The platform provides inbox placement testing and reputation indicators that help users monitor the health of each connected account. GMass records bounce rates and spam folder percentages during warm-up, allowing users to intervene when metrics decline. This system supports scaling into larger campaigns after warm-up has reached consistent performance benchmarks.

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10. Smartlead.ai

Smartlead.ai features a fully integrated email warm-up system designed for cold outreach at scale. It distributes emails across multiple inboxes and simulates engagement such as replies and folder adjustments. The warm-up system begins with low daily volume and scales as sender performance stabilizes. It adjusts timing and frequency to avoid detection by spam filters.

Users receive detailed reports showing inbox activity, bounce tracking, spam placement rates, and domain trust scores. Smartlead.ai also supports automated repair of sending reputation by modifying content or delivery timing. It is used for preparing large volumes of outbound mail without impacting sender identity or engagement rates.

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11. Artisan

Artisan uses an AI-driven engine to warm up inboxes and improve domain-level deliverability. The tool sends messages to verified inboxes and simulates natural interaction, including reads, replies, and removal from spam. The system adapts sending behavior daily based on health scores, bounce patterns, and blacklist status.

Artisan includes tools that test authentication records and adjust email pacing according to domain condition. It provides inbox placement metrics segmented by provider, such as Gmail and Outlook, and alerts users to anomalies in delivery results. The warm-up system is typically used for new inboxes, or after a domain has faced reputation damage.

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12. Woodpecker

Woodpecker includes warm-up capabilities focused on preventing deliverability issues in cold outreach. It rotates sending across multiple inboxes and adjusts sending patterns to match known safe thresholds. Engagement simulation includes reply detection, message marking, and interaction threading.

Reports within the platform provide breakdowns of spam folder placement, open tracking, and bounce distribution. Woodpecker emphasizes gradual increases in daily send volume and includes fail-safes if a domain starts to decline in reputation. Users managing multiple accounts can assign separate warm-up schedules and view performance individually.

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13. Reply.io

Reply.io features a warm-up module that operates by sending test messages between connected inboxes to build sender credibility. Each message is handled to resemble typical user interaction, and responses are logged to increase engagement scores. This system helps prepare new domains or email accounts for outbound messaging.

The warm-up performance dashboard tracks engagement rates, folder placement, and authentication status. Users can set different warm-up rules per inbox and monitor delivery behavior in real time. Reply.io also integrates warm-up data with the campaign module to ensure smooth transition to active outreach without triggering filters.

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Salesblink includes a warm-up tool aimed at establishing domain credibility through automated interactions. The system sends small batches of emails daily, incrementally raising volume while tracking delivery status. Messages are exchanged across a network of real inboxes and responses are logged to simulate genuine conversation.

Users receive placement analysis and spam folder reports, and are alerted if bounce rates rise above safe thresholds. The system tracks warm-up duration, suggesting when it is safe to move forward with active campaigns. Salesblink allows for warming multiple domains simultaneously, each with independent metrics.

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15. Mails.ai

Mails.ai provides warm-up automation alongside its email outreach features. The tool sends messages to trusted inboxes and ensures they are replied to, opened, and archived properly. It adjusts send limits each day based on performance and warns users when DNS issues or provider flags are detected.

The platform includes warm-up tracking for spam placement, inbox ratio, and daily engagement changes. It supports domain-specific configuration and enables senders to verify deliverability before scaling campaign size. Mails.ai also offers deliverability diagnostics to identify technical problems during the warm-up phase.

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16. SmartReach

Smartreach integrates inbox warm-up by connecting to Gmail, Outlook, and SMTP accounts and automating the process of sending, replying, and engaging with emails. It gradually increases the number of emails sent per day based on observed inbox behavior and response patterns.

Deliverability insights are shown in a unified dashboard, with metrics for spam filtering, engagement simulation, and inbox hit rate. Smartreach also logs spam alerts and provides a visual representation of warm-up progression. This system helps align new sender domains with safe outreach practices before campaign launch.

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17. Mailshake

Mailshake includes a warm-up feature for ensuring that new accounts are gradually prepared for bulk email activity. It controls initial sending volumes and simulates replies and opens across trusted addresses. This helps maintain sender reputation and reduces the chance of being flagged by spam filters.

Metrics from warm-up activity include inbox placement, bounce frequency, and open interaction. Mailshake uses these indicators to determine when an inbox is ready for high-volume outreach. The system integrates with the main campaign manager so that once warm-up is complete, users can begin sending without disruption.

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Conclusion

Warming up your email account is a crucial step for improving deliverability and avoiding spam filters, especially when launching cold outreach or using a new domain. The tools covered in this list provide automation, reputation management, and performance tracking to help maintain a healthy sender profile.

Each solution offers different strengths, from AI-driven sequences and inbox rotation to engagement simulations and analytics. Whether you're managing a few inboxes or operating at scale, selecting the right warm-up tool ensures that your emails reach the inbox, not the junk folder.

When choosing a platform, consider how it fits with your existing workflows, CRM, and outreach goals. A reliable warm-up process sets the foundation for successful campaigns, helping you build trust with providers and increase response rates over time.

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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