Growth Engine X

Growth Engine X was one of the first Clay-native outbound agencies and remains the reference point for cold email at volume. Eric Nowoslawski’s team sends millions of emails a month across client accounts, and the depth shows up in the parts most agencies treat as an afterthought: domain and inbox architecture, backup sending domains, deliverability monitoring, and enrichment that holds together at scale. Clay, Instantly, and Notion are among the named clients. They also publish their fit criteria openly, which saves everyone a call: roughly $1M+ in revenue, a target market above 100,000 contacts, customer lifetime profit over $5,000, and a sales team ready to take the meetings. Note their site currently serves from coldoutbound.com.