Case study · Klaviyo
Personalized Send Time
PESTO sends each message when that specific person is most likely to open it. I designed the scheduling UX, manual controls, and analytics that made marketers trust it.
Background
Tuesday at 10am. Everyone. All at once.
Most campaigns send everyone at the same moment. But your customers live on different schedules — and the existing Smart Send Time had gaps: no time windows, an invisible experiment baseline, and results nobody trusted. One large customer (Marley Lilly) churned over this, reporting Attentive's version doubled their revenue.
Design thinking
Build on what people already know.
I tested two entry points. The dropdown won — it plugged into the existing "send type" selector marketers already used, making the new behavior feel like a natural next step.
Toggle — too binary, doesn't communicate a window
Dropdown · chosen — familiar pattern, lower cognitive load
Customer selected controls
Make the experiment visible.
The original PST ran a silent A/B test against an invisible baseline. I designed the customer selected controls system — giving marketers visibility into what they're comparing against, without breaking analytics integrity.
Scheduling drawer — define a window, Klaviyo finds the right moment for each person
Analytics
Trust is built through proof.
Campaign-level: send time distribution vs. control. Account-level: headline lift across all campaigns. The question marketers ask is "is this working?" — I made sure they could answer it fast.
Campaign analytics — send time distribution vs. control group
Aggregate lift — orders, clicks, opens across all campaigns using PST
Impact