If you also have issues with your Dataverse storage, and Email activity table is used very often in your environment, then this is good news for you. Since May 2023, Microsoft planned to move old email descriptions of your environment into the Azure Blob storage. It is a background process running by Microsoft and you don’t need to do anything. From the user’s perspective, there would not be any change. But, admins can see the changes in consuming the storage.
Microsoft will move all email descriptions older than twelve months into Azure Blob storage, and when it is done, every 30-60 days a migration job runs to move the 12-month-old descriptions again.
For more information, please take a look at Email storage.