Specifically if you track down why your drive is getting full, and you find substantial data in this folder:
\\MailboxServerName\e$\Program Files\Microsoft\Exchange Server\V15\TransportRoles\data\Temp
Adjust this path to represent your own install path.
Then this is more than likely due to a bug in Exchange 2013's malware system. This folder should be kept clean, but a bug leaves behind a file for every message scanned. These can safely be deleted.
This bug is fixed in CU5