Time-based retention policies: With a time-based retention policy, users can set policies to store data for a specified interval. When a time-based retention policy is set, objects can be created and read, but not modified or deleted. After the retention period has expired, objects can be deleted but not overwritten. https://docs.microsoft.com/en-us/azure/storage/blobs/immutable-storage-overview?tabs=azure- portal https://docs.microsoft.com/en-us/azure/storage/blobs/immutable-time-based-retention-policy- overview