Out of stock – reminder
Instead of having people leaving the site when products are out of stock, Boomerang used a reminder campaign triggered by link clicks.
When a product size is back in stock, they send a reminder. This helps Boomerang both with collecting email addresses, to build an email list, but also with enriching the email database and the target audience with clothing size information.
They used one campaign to show a popup for visitors who clicked on a link on product pages, when certain sizes were out of stock.