An administrator identifies that, over the past week, the Cisco ESA is receiving many emails...

The appliance enforces your organization’s policies for messages sent to and from your users through the use of mail policies. These are sets of rules that specify the types of suspect, sensitive, or malicious content that your organization may not want entering or leaving your network. This content may include:

-spam

-legitimate marketing messages

-graymail

-viruses

-phishing and other targeted mail attacks

-confidential corporate data

-personally identifiable information

https://www.cisco.com/c/en/us/td/docs/security/esa/esa11-1/user_guide/b_ESA_Admin_Guide_11_1/b_ESA_Admin_Guide_chapter_01001.html?bookSearch=true