common/PendingEmails/Message.cs

namespace PendingEmails
{
    public static partial class Program
    {
        public class Message
        {
            public Message(int messageId, string sender, string subject, string body, string recipients, string recipientsCC)
            {
                this.Id = messageId;
                this.Sender = sender;
                this.Subject = subject;
                this.Body = body;
                this.Recipients = recipients;
                this.RecipientsCC = recipientsCC;
            }

            public int Id { get; set; }

            public string Sender { get; set; }

            public string Subject { get; set; }

            public string Body { get; set; }

            public string Recipients { get; set; }

            public string RecipientsCC { get; set; }

            public bool IsValid => !string.IsNullOrWhiteSpace(this.Recipients);
        }
    }
}