Which tool should you use first to troubleshoot Mail connectivity issues in macOS?

Connection Doctor is a built-in tool in Mail that helps you diagnose and fix problems with your email accounts and connections. It shows the status of each account, whether it is online or offline, and any errors that occurred. It also lets you test the connection to the incoming and outgoing mail servers, and view the details of the connection attempt. Connection Doctor is the first tool you should use when you encounter Mail connectivity issues in macOS, as it can help you identify the source and nature of the problem quickly and easily.  References : =  Apple Device Support Exam Prep Guide , page 11; [Mail User Guide for Mac], section “Check the status of your email accounts”.