A welcome series is a list-triggered flow that sends automatically when someone is added to a list — via a signup form, subscribe page, manual import, or the API. Klaviyo provides a pre-built welcome series in the Flows tab, and more advanced options in the Flow Library. Based on research across thousands of Klaviyo customers, three emails leads to optimal performance: send the first immediately after signup, a second two days later (social proof or brand story), and a third after four days (best-selling products). You can extend this to four or five emails if it fits your brand. Once subscribers finish the welcome flow, continue the relationship through campaigns rather than adding more emails to the flow itself — flows are designed for short-term, event-triggered automation, while campaigns handle ongoing communication.
If your signup forms capture both new subscribers and existing customers, use a conditional split to send each group different messaging — a first-purchase nudge for non-buyers, and a thank-you or brand intro for those who've already ordered.
Full community discussion | Help Center: create a welcome series | Klaviyo Academy: getting started with flows
