Warmbox

Automated inbox warmup service using a private seed network, for founders and sales teams running cold email.

Warmbox sends, opens, and replies to messages from a connected mailbox across a network of private inboxes, and moves messages out of the spam folder. It supports Gmail, Outlook, Yahoo, Amazon SES, SendGrid, and custom SMTP, with growth, flat, or randomized ramp patterns. Spam score monitoring plus DNS and blacklist checks run alongside the warmup, and it does not send campaigns.