1. Shipping Events Overview
Postflows automates post-purchase notifications by listening for shipping events - milestones that occur as your customer's order moves from checkout to delivery. This article explains how events work and what happens when one fires.
What is a shipping event?
A shipping event is a specific moment in the fulfillment lifecycle - a label being created, a package entering transit, a delivery being completed. When one of these moments occurs for an order, Postflows detects it and forwards it to your email platform (Klaviyo or Omnisend), which then sends the corresponding notification to your customer.
Postflows supports 8 shipping events. See Available Events and What Triggers Each One for the full reference.
How events flow through Postflows
Every event goes through three checks before reaching your email platform:
Event detected → Rules evaluated → Sent to email platform
Event detected - Postflows receives an update from Shopify or your carrier
Rules evaluated - Order filters and event filters determine if this order and event should be processed
Sent to email platform - If all checks pass and the event is enabled, Postflows forwards it to Klaviyo or Omnisend
If any check blocks the event, it's dropped silently - no email is sent.
Events are real-time
Events fire immediately when the carrier update is received. There is no delay or scheduling - as soon as Postflows processes the update, it's forwarded to your email platform.
The only exception is Order Created, which fires directly from Shopify when the order is placed - no carrier tracking is involved.
Events vs. emails
Postflows forwards events - it does not send emails itself. The email is built, personalized, and sent by Klaviyo or Omnisend using the event data Postflows delivers.
This means:
Your email templates, branding, and copy live entirely in your email platform
You control timing, content, and audience segmentation there
Postflows is responsible only for detecting events and delivering the data
Enabling and disabling events
All 8 events are enabled by default. You can turn any of them off from the dashboard at any time - see Enabling and Disabling Events.