[tony-allan]

Keep it simple -- how often do you need to send the emails? One a day, once an hour, after you update your stock items. Just check periodically.

Do you want to consolidate emails if a user had multiple alerts?

[samrohn777]

Email has to be triggered once an hour since the items are fast moving. There is no need to consolidate multiple emails into one. We have around 50k products and stock levels are at fullfillment location level(100+ locations). We capture the zip code of the user as well so as to trigger email if the item is back at fullfillment location near to him.