Email warm-up that's free, automatic, and never billed
Warm up unlimited inboxes automatically. AlienMail ramps sending volume, builds sender reputation and monitors placement — with zero monthly fees.
No credit card required · Free unlimited warmup included · 250 free credits
Email warm-up gradually increases sending volume from a new inbox while generating positive engagement signals — opens, replies, and moves out of spam — so mailbox providers learn to trust your domain. AlienMail warms every connected inbox automatically from the day you connect it, and warm-up emails are never counted toward your billing.
How it works
A modern, three-step pipeline engineered for inbox delivery and high conversion.
Connect any mailbox provider
Connect your Google Workspace, Microsoft 365, Zoho, or custom SMTP/IMAP inboxes with 1-click OAuth2 or SMTP authentication.
Automated peer network warmup
AlienMail automatically sends, receives, opens, and replies to dynamic conversational threads across a network of verified peer inboxes.
Gradual volume ramping & monitoring
Sending volume ramps up progressively from 2 to 40+ daily emails with continuous reputation scoring to ensure primary inbox deliverability.
Why new domains need automated email warm-up
When you register a fresh domain and start sending high-volume cold emails immediately, major email service providers like Google and Microsoft flag your sender IP and domain as suspicious. Automated email warm-up simulates organic human correspondence over a 2 to 4 week period, building a reliable sender reputation before launching your sales campaigns.
Smart AI engagement with human-like conversation threads
Spam filters inspect more than just send volume—they analyze message content, reply speed, and engagement ratios. AlienMail uses AI-generated contextual replies that are automatically marked as important, opened, and saved from spam folders, signaling top-tier sender quality to mailbox algorithms.
Warm-up is 100% free and never billed against your email credits
Standalone warm-up services charge anywhere from $25 to $49 per inbox per month. AlienMail believes deliverability is a fundamental requirement, not a paid add-on. Connect unlimited inboxes and run background warm-up indefinitely without spending a cent on warm-up sends.
AlienMail vs Standalone Warm-Up Tools
Verified August 2026. Competitor pricing based on published public plans.
| Feature / Capability |  AlienMail | Instantly | Mailreach | Warmy.io |
|---|---|---|---|---|
| Pricing & Inboxes | ||||
| Monthly platform fee | $0 (Pay per send) | $47 / mo min | $25 / mo / inbox | $49 / mo / inbox |
| Warm-up cost per inbox | $0 (Free) | Included in $47+ plan | $25 / inbox | $49 / inbox |
| Inboxes supported | Unlimited | Unlimited | 1 per license | 1 per license |
| Warm-up emails billed separately? | Never (100% Free) | No | No | No |
| Deliverability Features | ||||
| Automated ramp-up schedule | ✓ Included | ✓ Included | ✓ Included | ✓ Included |
| AI-generated conversational replies | ✓ Included | ✓ Included | ✓ Included | ✓ Included |
| Spam folder rescue & importance marking | ✓ Included | ✓ Included | ✓ Included | ✓ Included |
| Built-in cold outreach engine | ✓ Included | ✓ Included | ✕ | ✕ |
| Real-time deliverability health score | ✓ Included | ✓ Included | ✓ Included | ✓ Included |
Proven 4-week email warm-up ramp schedule
AlienMail automates volume ramping according to ISP best practices to ensure gradual, safe domain reputation growth.
| Phase | Timeline | Daily Warm-Up Sends | Target Reply Rate | Recommended Cold Sends |
|---|---|---|---|---|
| Initial Ramp | Week 1 (Days 1–7) | 2 – 10 emails/day | 30% – 45% | 0 emails/day (Warmup only) |
| Reputation Building | Week 2 (Days 8–14) | 10 – 25 emails/day | 35% – 50% | 5 – 10 cold emails/day |
| Scaling Outbound | Week 3 (Days 15–21) | 25 – 35 emails/day | 35% – 45% | 15 – 25 cold emails/day |
| Production Baseline | Week 4+ (Ongoing) | 35 – 50 emails/day | 30% – 40% | 30 – 40 cold emails/day/inbox |
Frequently Asked Questions
Everything you need to know about AlienMail features and deliverability.
What is email warm-up and how does it work?
Email warm-up is the process of gradually increasing the send volume from a new email account while generating positive engagement (opens, replies, marking as important, moving out of spam). This establishes a positive sender reputation with Internet Service Providers (ISPs) like Google Workspace and Microsoft 365 so your outreach lands in the primary inbox.
How long does email warm-up take before I can send campaigns?
We recommend warming up a brand-new domain for at least 14 to 21 days before launching live outreach campaigns. For aged domains with existing reputation, 7 to 10 days is usually sufficient.
Is email warm-up safe, and can it get my domain banned?
Yes, AlienMail's automated warm-up is completely safe because it operates within provider-recommended daily send thresholds and utilizes authentic peer-to-peer network interactions rather than synthetic bot traffic.
Do warm-up emails count toward my billing on AlienMail?
No. Warm-up emails are 100% free and are never counted toward your paid email send credits.
Can I warm up unlimited inboxes?
Yes. You can connect and simultaneously warm up as many inboxes across Google Workspace, Microsoft 365, Zoho, or custom SMTP servers as your team needs.
Does warm-up work with Gmail, Outlook, and custom SMTP?
Yes. AlienMail supports OAuth2 connections for Google Workspace and Microsoft 365, as well as IMAP/SMTP connections for any custom email server.
Do I need to keep warm-up running after campaigns start?
Yes. Keeping warm-up active alongside live sales campaigns maintains a healthy ratio of opens and replies, protecting your inbox from deliverability dips when sending cold outreach.
What is the difference between domain warm-up and IP warm-up?
Domain warm-up builds reputation for your specific sending domain name (e.g. yourcompany.com) across mailbox providers, while IP warm-up establishes reputation for dedicated sending IP addresses. Most outbound senders rely primarily on domain reputation.
Can I warm up a brand-new domain?
Yes. Starting with proper DNS authentication (SPF, DKIM, DMARC) and running automated warm-up is the essential first step before sending any sales outreach on a new domain.
What happens if I pause warm-up?
If you pause warm-up, your inbox will no longer exchange peer interactions. While existing reputation doesn't disappear immediately, prolonged inactivity or sudden bursts of cold emails can cause deliverability to drop.
Related Features & Guides
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Cold Email Software
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Email Verification
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AlienMail vs Instantly
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Instantly Alternatives
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Transparent Pricing
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Protect your domain reputation today
Connect unlimited inboxes, start automated warming for free, and launch cold email campaigns with confidence.