Instantly.ai

Instantly.ai is a cold email platform designed specifically for scaling outreach campaigns using multiple sender mailboxes. Founded in 2021, it rapidly became one of the most popular cold email tools among growth hackers, lead generation agencies, and sales teams, primarily because of its unlimited mailbox model: all paid plans allow connecting unlimited email sending accounts (Gmail, Outlook, custom SMTP), enabling users to scale sending volume without paying per mailbox. The platform includes a built-in email warmup system (Warmup Network) that automatically exchanges emails between Instantly accounts to build sender reputation before real campaigns launch. The campaign builder supports AI-powered personalization using custom variables and dynamic text insertion. The analytics dashboard tracks open rates, click rates, reply rates, and booked meetings. Instantly also includes a B2B lead database with over 160 million verified contacts, allowing users to find and import prospects directly within the platform. In 2026, Instantly expanded with CRM-lite features for tracking lead stages, a unified inbox for managing all replies across mailboxes, and improved AI sequence writing. The platform is dominant in the agency and growth hacking community where scaling sending infrastructure is a core requirement.