// The send email command
    public class SendEmailCommand : ICommand
    {
        [Required]
        [EmailAddress]
        [StringLength(256)]
        public string From { get; set; }

        [Required]
        [EmailAddress]
        [StringLength(256)]
        public string To { get; set; }

        [Required]
        [StringLength(256)]
        public string Subject { get; set; }

        [Required]
        public string Body { get; set; }
    }

    // The sent email event
    public class EmailSent : IEvent
    {
        public EmailSent(string from, string to, string subject)
        {
            this.From = from;
            this.To = to;
            this.Subject = subject;
        }   

        public string From { get; set; }

        public string To { get; set; }

        public string Subject { get; set; }
    }

    // Command without return value
    var command = new SendEmailCommand
    {
      From = "address@email.com",
      To = "to_address@email.com",
      Subject = "Hello !",
      Body = "Hello World !"
    };
    
    // processor should be a singleton for better performance
    using (CommandProcessor processor = new MessageProcessor())
    {
      // The processor will find the handler and delegates to it the action
      await processor.ProcessAsync(command);
    }

    public class EmailSender : MessageHandler, 
        IAsyncCommandHandler<SendEmailCommand>
    {
        public Task HandleAsync(SendEmailCommand command)
        {
            // Email sending logic here.

            // Sent an event to indicate that the email was sent.
            EmailSent emailSent = new EmailSent(command.From, command.To, command.Subject);
            return this.CommandContext.Request.Processor.PublishAsync(orderCreated);
        }
    }