The project and its services, including Redis, still exist, but there are currently no volumes in that project, so neither scarecrow-volume nor the Redis disk from the email you received is attached to anything now.

A deleted volume can only be restored while its deletion is still pending, from the project's Activity feed by finding the volume deletion entry and clicking Restore. If no Restore option appears there, redeploying Redis or the other services will start them without the previous data.