How to determine if STARTTLS has been successfully executed and the connection has been securely upgraded (e.g. to TLS 1.2)

[ahhhbish]

Hi, so basically the title. Currently I am looking into detecting when a "STARTTLS" occurs OnCommandExecuted() and then checking for "MAIL" commands in OnCommandExecuting() -> if STARTTLS hasn't been executed then no MAIL commands are allowed. Is this a reliable way to do what I want?

[ahhhbish]

Just for information, I will add a hook into the OnCommandExecuting() callback.
If the e.Command.Equals("MAIL") then I will check e.Context.Pipe.IsSecure.
The only question then is how to prevent the MAIL command from being executed if it should not be?