Back-in-stock alerts in batches
When a sold-out size comes back, alerting everyone at once can sell it out in minutes and leave most people with a link to an out-of-stock product.
trigger: the product is back in stock
audience: asked to be notified for that size and color
sending: batches of 20% every 30 minutes
if it sells out: stop sending and move the rest to a waitlistRecommendation. Order the batches by how long ago people asked to be notified: the first to ask is the first to know.