Its a new concept raising in Security area, Sandbox is a type of restricted Area where untested or unverified programs or malicious code will be executed and checked . Traditional issue in security field is one the malicious code is attacked to the network then only patch or security of the code will be released. Sandbox is the solution provider even if the e-mail contained unverified program, any malicious code it will go sandbox virtualized area first and the code will be tested. after the code is executed there is no issue found in Sandbox virtualization environment the software or program will allowed in to the internal network.
If sandbox found a hacking or virus program , it will block the software and it will added as a virus batch thus it not allowing to enter our network, so we will have full secure environment.