Case Study: Prometheus migrates 1.5M subscribers and protects sender reputation with Yespo CDP

Prometheus migrates 1.5M contacts to Yespo in 8 weeks without losing sender reputation

Prometheus, a large online educational platform, faced challenges scaling its email marketing after its subscriber base grew to 3 million. Its existing email service provider (ESP), Sendy, required manual data management and lacked the advanced segmentation and analytics needed for targeted communication. To overcome these limitations and enable further growth, Prometheus partnered with the vendor Yespo to migrate to its Customer Data Platform (CDP).

Yespo implemented a carefully planned "parallel start" migration strategy to move 1.5 million active subscribers without pausing communications or damaging sender reputation. The solution included a structured 8-week domain warm-up process, supported by Yespo's analytics and expertise. As a result, Prometheus successfully warmed up its domain to send to over 1.35 million contacts while maintaining a high sender reputation, and achieved dramatically higher engagement, including an open rate of 68.6% for a key giveaway results email.

Prometheus