NETCore3Demo/EventDemo/NewMailEventArgs.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace EventDemo
{
    /// <summary>
    /// 定义一个附加信息类，用来通知接收者发生了什么。 即 事件本身
    /// </summary>
    public class NewMailEventArgs :EventArgs
    {
        public string From { get; }
        public string To { get; }
        public string Content { get; }

        public NewMailEventArgs(string from, string to, string content)
        {
            From = from;
            To = to;
            Content = content;
        }
    }
}