The organization's new email system should provide e-discovery functionality. E-discovery stands for electronic discovery, which is the process of identifying, preserving, collecting, processing, reviewing, analyzing, and producing electronically stored information (ESI) that is relevant to a legal matter. E-discovery can help the organization comply with legal holds, which are orders or notices to preserve relevant ESI when litigation is anticipated or ongoing. E-discovery can also help the organization reduce the costs and risks of litigation, as well as improve the efficiency and accuracy of the discovery process.

These are percentages of total CPU time.
us: Time spent running non-kernel code. (user time, including nice time) sy: Time spent running kernel code. (system time) id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.

Reference: https://www.rapid7.com/blog/post/2017/10/04/how-to-secure-ssh-server-using-port- knocking-on-ubuntu-linux/