Before this build, transactional and event-triggered emails ran through a tangle of methods — some just-in-time, some batched, populated from templates that lived partly in the application and partly in outside tools, then routed to whichever of three different ESPs happened to handle that trigger. Promotional sends lived in yet another system entirely, consent and subscription data were scattered across all of them, and only Engineering could make a change — which meant marketing owned the revenue number but had no way to test content, fix broken tracking, or add a new campaign without competing for engineering time.
I built the business case first — modeling the cost and revenue impact of consolidating onto a single platform — and used it to get this prioritized as a major engineering initiative rather than a background task. I then wrote a requirements doc, evaluated eight-plus ESPs against cost, flexibility, and API fit, and selected Klaviyo.
Before the build, I audited every active campaign to decide what to keep, edit, or kill, then defined the full event and data architecture, including a new subscription framework that let account managers customize communications at the partner level. Engineering delivered the API integration; I used it to build 20+ user-based flows, 10+ transactional campaigns, and a monthly promotional workflow per audience, and we wrote new-event requirements into the standard engineering build process going forward.