Instantly

Instantly is the cold email platform Nils Schneider and Tina Phung bootstrapped in 2021, growing to $10M+ ARR in under three years by solving the deliverability problem that limits all cold email: you can only send 100-200 emails per day per inbox before hitting spam filters. Instantly's solution was unlimited inbox rotation — connect 10 inboxes and Instantly distributes sends across all of them, maintaining safe per-inbox volumes while dramatically increasing total sending capacity. The built-in email warmup network was the product's breakthrough: a network of real sending accounts that automatically interact with each other's emails (open, reply, mark as important) to build sender reputation for new inboxes. Users could launch a brand new domain, warm up for 2 weeks, and start cold emailing at scale without deliverability problems. Instantly grew through Twitter and YouTube — the founders documented their growth and shared cold email tactics publicly, building an audience of salespeople who converted to paying customers as the content drove trust.