C# 如何发送邮件消息

using MailKit.Net.Smtp;
using MimeKit;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Threading.Tasks;

namespace WebApplication1
{
    public class MailHelper
    {
        /// <summary>
        /// 发送电子邮件
        /// </summary>    
        /// <param name="subj">邮件标题</param>
        /// <param name="bodys">邮件内容</param>
        /// <param name="mailData">发送邮件需要的基本参数信息</param>
        /// <returns></returns>

        public async Task SendMail(string subj, string bodys, SaleMail mailData)
        {
            #region 发邮件需要的基本参数

            var fromMail = mailData.LoginAccount; //发件人邮箱账号
            var pwd = mailData.LoginPwd;//发件人邮箱登录密码

            var toMail = mailData.ReceivedUser;//接收人邮箱账号，多个接收人用逗号分割开
            var otherUser = mailData.ReceivedOtherUser;//抄送人邮箱账号，多个抄送人用逗号分割开

            var smtpserver = mailData.MailServer;//邮箱服务地址 // smtp.mxhichina.com
            var port = mailData.MailPort;//邮箱端口：25

            if (string.IsNullOrWhiteSpace(smtpserver) ||
                port <= 0 ||
                string.IsNullOrWhiteSpace(fromMail) ||
                string.IsNullOrWhiteSpace(pwd) ||
                string.IsNullOrWhiteSpace(toMail))
            {
                return;
            }

            #endregion

            #region 发送内容
            var bodyType = "html"; //暂时只支持html类型的，Body里面可以支持其余类型
            var message = new MimeMessage
            {
                Subject = subj,//邮件标题
                Body = new TextPart(bodyType) //有其余类型消息体类型可以支持
                {
                    Text = bodys
                }
            };
            #endregion

            #region 发送人
            message.From.Add(new MailboxAddress("", fromMail));//发送人
            #endregion

            #region 收件人

            var toMailList = new List<string>();
            if (!string.IsNullOrWhiteSpace(toMail))
            {
                toMailList = toMail.Split(',').ToList();
            }
            foreach (var item in toMailList)
            {
                var curToMail = item.Trim();
                if (string.IsNullOrWhiteSpace(curToMail))
                {
                    continue;
                }
                message.To.Add(new MailboxAddress("", curToMail));//接收人

            }

            #endregion

            #region 抄送人
            var others = new List<string>();
            if (!string.IsNullOrWhiteSpace(otherUser))
            {
                others = otherUser.Split(',').ToList();
            }
            foreach (var s in others)
            {
                var curOther = s.Trim();
                if (string.IsNullOrWhiteSpace(curOther))
                {
                    continue;
                }
                message.Cc.Add(new MailboxAddress("", curOther));
            }

            #endregion

            #region 进行发送邮件

            SmtpClient smtpClient = new SmtpClient();
            smtpClient.Connect(smtpserver, port);//建立连接：邮箱服务地址与端口
            smtpClient.Authenticate(fromMail, pwd);//发件人邮箱登录密码与登录账号            
            await smtpClient.SendAsync(message);//邮件传送
            smtpClient.Disconnect(true);//连接释放

            #endregion

        }

    }

    /// <summary>
    /// 发送邮件需要的基本参数信息实体
    /// </summary>
    public class SaleMail
    {

        /// <summary>
        /// 邮箱登录人(发送人)账号
        /// </summary>
        [Required]
        [StringLength(200)]
        [DefaultValue("")]
        public string LoginAccount { get; set; }


        /// <summary>
        /// (发送人)邮箱登录密码
        /// </summary>
        [Required]
        [StringLength(200)]
        public string LoginPwd { get; set; }


        /// <summary>
        /// 接收人（多个按照逗号隔开）
        /// </summary>
        [Required]
        [StringLength(200)]
        [DefaultValue("")]
        public string ReceivedUser { get; set; }

        /// <summary>
        /// 抄送人（多个按照逗号隔开）
        /// </summary>
        [Required]
        [StringLength(200)]
        [DefaultValue("")]
        public string ReceivedOtherUser { get; set; }


        /// <summary>
        /// 邮箱服务地址(smtp.mxhichina.com)
        /// </summary>
        [Required]
        [StringLength(200)]
        [DefaultValue("")]
        public string MailServer { get; set; }


        /// <summary>
        /// 邮箱端口（25）
        /// </summary>
        [Required]
        public int MailPort { get; set; }

    }
}