Buy Again is a unique stage in your post-purchase email campaign. It's an opportunity to send a targeted message at a calculated interval to drive repeat purchases of specific items.
The Buy Again stage is powered by the replenish_interval variable. Replenish_interval is the number of days after a purchase you want to send your Buy Again email. For example, if you sell small and large vitamin bottles, the small bottle might have a 30 day replenishment interval, while the large bottle would have 180 days.
When building your Buy Again email, use a single product recommendation. Secondary recommendations are not currently supported for replenishment.
Replenish_interval needs to be set for any item to get a Buy Again send. Shopify customers can use Shopify Metafields to set replenish_interval, all other accounts will need to use flat file import.