A server running Windows Server hosts an application App1. You must block App1 from reaching external SMTP servers while minimizing impact on App1's access to external HTTP, minimizing effects on other applications on the server, and minimizing administrative effort. Which Windows Defender Firewall configuration should you implement?

An outbound program rule is the most precise solution. It allows you to specify the executable for App1 and block its outbound connections only to the SMTP port (typically TCP 25), leaving other applications and App1's HTTP access unaffected. An inbound custom rule would block incoming connections, not outbound. An outbound custom rule is too broad; while it could block SMTP, it would require more complex filtering to ensure only App1 is affected, or it might impact all applications. An inbound program rule is for incoming connections. An outbound port rule would block all applications on the server from using the SMTP port, which is not minimizing impact on other applications.