W
Sales
AI email warm-up tool to keep cold emails out of spam
Email WarmupCold EmailDeliverability
Warmbox is an AI-based email warm-up tool that raises your inbox reputation so cold email campaigns land in the primary inbox instead of spam. It automatically sends and interacts with emails like a real person would — opening, replying, marking as favorite, and removing from spam — using a network of 35,000+ private inboxes, with detailed deliverability reporting.
- Best for
- Sales and marketing teams running cold email campaigns who need to protect sender reputation and keep outreach out of spam folders.
- Pricing
- No free plan. Paid plans from $15/mo (Solo, 1 inbox) to $139/mo (Growth, 6 inboxes); custom Team plans available for larger needs.
Core features
- • Automated email warm-up with human-like opens, replies, and favoriting
- • Auto-remove from spam and spam score monitoring
- • 35,000+ private inbox network across major email providers
- • Growth, flat, random, or fully custom warm-up schedules
- • Live Email Checker for DNS and blacklist status
- • Detailed reporting and inbox reputation dashboard
- • Multi-account support for agencies with team members
- • Integrations: Gmail/GSuite, Outlook 365, Yahoo, iCloud, Zoho, Sendgrid, Amazon SES, and any SMTP inbox
Use cases
- 1. Warming up a new mailbox before starting a cold email campaign
- 2. Recovering sender reputation after emails started landing in spam
- 3. Agencies warming up multiple client inboxes from one dashboard
- 4. Monitoring inbox reputation and spam score over time
- 5. Checking a domain's DNS/blacklist status before sending
How to use
Connect your inbox from your email provider (OAuth for Gmail/Outlook, or SMTP for others) in a couple of minutes, choose a warm-up schedule (growth, flat, random, or custom), and let Warmbox send and interact with emails automatically. Monitor your inbox reputation and spam score in the dashboard as deliverability improves.
Pricing plans
Solo
$15/mo
- • 1 inbox warm-up
- • 50 emails/day
- • 1 member
- • Premium support
Start-up
$69/mo
- • 3 inbox warm-up
- • 250 emails/day
- • 3 team members
- • Premium support
Growth
$139/mo
- • 6 inbox warm-up
- • 500 emails/day
- • 6 team members
- • Enterprise support
FAQ
Is Warmbox free?
No — Warmbox is a paid tool starting at $15/mo for one inbox, with no permanent free plan.
Which email providers does Warmbox support?
Gmail/GSuite, Outlook 365, Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Sendinblue, Mailgun, Amazon SES, and any other inbox via SMTP.
How do I know when my inbox is warmed up?
Warmbox provides a reporting dashboard that tracks your inbox reputation and spam score over time, so you can see deliverability improve as the warm-up progresses.
Where it holds up
- Automated, human-like interactions (open, reply, favorite, remove from spam) build sender reputation without manual work
- 35,000+ private inbox network to warm up against, across major providers
- Works with virtually any inbox: Gmail, Outlook, Yahoo, Zoho, Amazon SES, SMTP, and more
- Live email checker for DNS/blacklist issues plus detailed deliverability reporting
- Multiple warm-up modes (growth, flat, random, fully custom) to match your sending pattern
Where it falls short
- No free plan — pricing starts at $15/mo with no free tier to test first
- Lower tiers cap warm-up to very few inboxes (1-3) and a low daily email volume
- A dedicated warm-up tool means running it alongside whatever platform you actually send campaigns from
