Case Studies

Most agencies treat client relationships as binary: pay the full retainer or walk. The Playbook Agency built a third option. By reselling InboxKit's infrastructure under their own brand, they gave budget-constrained clients somewhere to land instead of somewhere to leave, cutting churn 80% and growing infrastructure revenue 30%.

In early 2026, Cymate's primary email vendor failed and reply rates collapsed across dozens of client campaigns. Rather than wait it out, founder Wesley Hoang ran a head-to-head vendor test. InboxKit came out ahead 2.6x on positive replies — and within three months Cymate had rolled it across their entire client base.

TGP, the largest prospecting agency in Latin America, was bleeding ops hours stitching together domains, Google Workspace, and email creation across five separate vendors. On InboxKit, that whole chain collapsed into a few clicks — dropping client onboarding from hours to minutes without touching their 15.2% reply rate.

In late 2025, a Google mailbox crackdown ran through the email world and hit agencies hardest. Rather than chase the next cheap workaround, Jayson DeMers of OutreachBloom moved to InboxKit mid-crisis — and has run OutreachBloom's email infrastructure on it ever since, at an 11.5% reply rate and a 0.6% bounce rate.

A multi-client GTM agency transformed manual mailbox setup into a fully automated, self-service operation. In six months on InboxKit, Anevo Marketing went from zero to 4,361 mailboxes under their own control and cut client setup time from one to two weeks down to one to two hours.

Managing 100+ client campaigns at scale meant abandoning manual infrastructure work. InboxKit's automation became the only way forward — automated DNS (zero manual hours), domain isolation, zero suspensions, and a 17% average reply rate.