Warmbox is an AI-based email warm-up tool that raises inbox reputation and deliverability for cold email senders. Once an inbox is connected, Warmbox automatically sends realistic emails from it and interacts with them the way genuine leads would, building the positive engagement history that mailbox providers use to decide whether future campaigns reach the inbox or the spam folder.
Warmbox works with a private network of more than 35,000 inboxes across major providers. Every day it sends emails from the connected inbox, removes them from spam, opens and bookmarks them, and replies to a portion of them, creating a steady pattern of positive interactions. The email content itself is generated with GPT-4 and hybrid models so messages read as human and realistic rather than templated. Warm-up behavior is fully customizable, with growth, flat, or random patterns and custom schedules. Detailed reports and AI monitoring track reputation and spam score over time, and a live email checker reviews DNS settings and blacklist status. More than 5,000 companies use the service.
Warmbox is a paid subscription service priced per inbox, with plans that scale from individual senders to agencies managing many client accounts. Setup takes a few minutes per inbox and requires no technical skills.
Warmbox is for cold email senders, sales teams, and lead generation agencies whose campaigns underperform because of spam placement, and who want an automated, set-and-forget way to build and maintain sender reputation.