Spotify Pre-Save is a new feature that allows your fans to "subscribe" and save your release date in order to remind them once it goes live on Spotify. It is included in the Indiefy Pro account, but can be purchased as an extra promotional tool in the free account.
You can find this tool in your artist dashboard, simply by clicking 'Promotion' and 'Presave Campaigns'. The option will be visible once you have sent in your release.
This an amazing way to spike your release and make it more visible to Spotify users, since once the release is live all that saved the release date will listen to it, allowing the Spotify algorithm to work and recommend your release to more listeners.