How To Check How Much Storage Space Is Currently In Use?
Go to https://www.filemail.com/myprofile#storage. Additionally you have a very quick overview in the website top bar just below your username - a small progress bar with a tooltip on it.
For company administrators there is another section showing information about all users in the company: https://www.filemail.com/CompanySettings#storage. From there a company administrator can also clean up transfers in order to reduce the size of used storage space.