Both those things you mention as wanting exist already.
For data storage independent billing, go to Settings -> Dashboard. On Professional tier and above the data storage is a dropdown where you can increase the amount required.
For email filtering go to Settings -> Filters and create as many conditions as you want on a filter.
For data storage independent billing, go to Settings -> Dashboard. On Professional tier and above the data storage is a dropdown where you can increase the amount required.
For email filtering go to Settings -> Filters and create as many conditions as you want on a filter.