Mail (also known as Apple Mail) is the email application included with Mac OS X.

Mail plus Apple's Calendar and Address Book apps can provide some of the functionality of Outlook, Microsoft's Exchange client, but not all. We recommend that you use Outlook or Outlook on the Web.

CIT supports the last two major versions of macOS with latest patch release for each of those versions.
As of July 15, 2021, CIT supports Apple Mail with 

• macOS 10.15 (Catalina)
• macOS 11.4 (Big Sur)