TrulyInbox

TrulyInbox automates email warmup by routing messages through thousands of real mailboxes across Gmail, Outlook, Yahoo, and other providers. The platform uses machine learning to mimic natural sending patterns and engagement, gradually building sender reputation before high-volume campaigns launch. It monitors each ESP's behavior and adapts strategies to match their filtering algorithms.

Best for teams warming up cold email sequences or preparing new domains before sales campaigns. Delivers faster reputation recovery than manual warmup and works across any email provider you send from. Compares favorably to competitors on connection count and the breadth of supported ESPs.