C# 发送 Email 功能：EmailHelper（群发，多附件）

第一篇文章，没想会是这个 EmailHelper。

最近在总结一般的网站建设中典型的模块和功能，今天下午到了 Email 这块，上网找了半天也没找到几个，不知道是太简单还是怎么回事。

好不容易搜了个出来，漏洞百出，一发就报异常，干脆自己写一个。

测试接收的邮箱有 163、126、qq、gmail、hotmail、sina，都没问题，可以多收件人、多附件发送。

另外，我在写的时候出了个小错误，在这里也提个醒：发件人邮箱的 smtp 服务必须开启才能发送成功。

还有不完善的地方，会继续改进。

下面贴代码：

using System;
using System.Net;
using System.Net.Mail;
using System.Text;

namespace Polin.Utility
{
    public class EmailHelper
    {
        #region Constructor

        public EmailHelper()
        { }

        #endregion

        #region Private Fields

        private string _mailSubject;
        private string _mailBody;
        private string _mailFrom;
        private string _mailFromName;
        private string _mailTo;
        private string _smtp;
        private int _smtpPort;
        private string _userName;
        private string _pwd;
        private MailPriority _mailPrioty;
        private string file;

        #endregion

        #region Public Properties

        /// <summary>
        /// 邮件主题，默认为 “无主题”
        /// </summary>
        public string MailSubject
        {
            get
            {
                if (string.IsNullOrEmpty(this._mailSubject))
                {
                    return "无主题";
                }
                return this._mailSubject;
            }
            set { _mailSubject = value; }
        }

        /// <summary>
        /// 邮件内容
        /// </summary>
        public string MailBody
        {
            get { return _mailBody; }
            set { _mailBody = value; }
        }

        /// <summary>
        /// 发件人地址（必填）
        /// </summary>
        public string MailFrom
        {
            get { return _mailFrom; }
            set { _mailFrom = value; }
        }

        /// <summary>
        /// 发件人名称，默认为 “系统邮件”
        /// </summary>
        public string MailFromName
        {
            get
            {
                if (string.IsNullOrEmpty(this._mailFromName))
                {
                    return "系统邮件";
                }
                return this._mailFromName;
            }
            set { _mailFromName = value; }
        }

        /// <summary>
        /// 收件人地址，多个收件人地址用逗号隔开（必填）
        /// </summary>
        public string MailTo
        {
            get { return _mailTo; }
            set { _mailTo = value; }
        }

        /// <summary>
        /// smtp 地址，如 smtp.163.com（必填）
        /// </summary>
        public string Smtp
        {
            get { return _smtp; }
            set { _smtp = value; }
        }

        /// <summary>
        /// smtp 端口，默认为 25
        /// </summary>
        public int SmtpPort
        {
            get
            {
                if (this._smtpPort == 0)
                {
                    return 25;
                }
                return this._smtpPort;
            }
            set { _smtpPort = value; }
        }

        /// <summary>
        /// 发件人账户，如 abc@163.com，则账户为 abc（必填）
        /// </summary>
        public string UserName
        {
            get { return _userName; }
            set { _userName = value; }
        }

        /// <summary>
        /// 发件人密码（必填）
        /// </summary>
        public string Pwd
        {
            get { return _pwd; }
            set { _pwd = value; }
        }

        /// <summary>
        /// 邮件等级：低、正常、紧急，默认为 正常
        /// </summary>
        public MailPriority MailPrioty
        {
            get
            {
                if (this._mailPrioty != MailPriority.Low && this._mailPrioty != MailPriority.High && this._mailPrioty != MailPriority.Normal)
                {
                    return MailPriority.Normal;
                }
                return this._mailPrioty;
            }
            set { _mailPrioty = value; }
        }

        /// <summary>
        /// 附件地址，多个地址用逗号隔开。Web 应用中请使用 Server.MapPath() 映射到实际地址
        /// </summary>
        public string File
        {
            get { return file; }
            set { file = value; }
        }

        #endregion

        #region Method

        /// <summary>
        /// 发送邮件
        /// </summary>
        /// <param name="error">输出参数：发生错误时返回错误信息</param>
        /// <returns>是否发送成功</returns>
        public bool SendMail(out string error)
        {
            error = string.Empty;
            if (!Valid(out error))
            {
                return false;
            }
            MailAddress mailFrom = new MailAddress(this.MailFrom, this.MailFromName, Encoding.UTF8);
            MailMessage mail = new MailMessage();
            mail.From = mailFrom;
            string[] mailToCollection = this.MailTo.Split(',');
            foreach (string s in mailToCollection)
            {
                MailAddress t = new MailAddress(s, "", Encoding.UTF8);
                mail.To.Add(t);
            }
            if (!string.IsNullOrEmpty(this.File))
            {
                string[] fileCollection = this.File.Split(',');
                foreach (string f in fileCollection)
                {
                    Attachment t = new Attachment(f);
                    mail.Attachments.Add(t);
                }
            }
            mail.Subject = this.MailSubject;
            mail.SubjectEncoding = Encoding.UTF8;
            mail.Body = this.MailBody;
            mail.BodyEncoding = Encoding.UTF8;
            mail.IsBodyHtml = true;

            SmtpClient smtp = new SmtpClient();
            smtp.Host = this.Smtp;
            smtp.Port = this.SmtpPort;
            smtp.Credentials = new NetworkCredential(this.UserName, this.Pwd);
            try
            {
                smtp.Send(mail);
                return true;
            }
            catch (Exception e)
            {
                error = e.Message;
                return false;
            }
        }

        /// <summary>
        /// 检查必填属性
        /// </summary>
        /// <param name="e">输出错误信息</param>
        /// <returns>是否有效</returns>
        private bool Valid(out string e)
        {
            e = string.Empty;
            if (string.IsNullOrEmpty(this._mailFrom))
            {
                e = "发件人地址不能为空";
                return false;
            }
            if (string.IsNullOrEmpty(this._mailTo))
            {
                e = "收件人地址不能为空";
                return false;
            }
            if (string.IsNullOrEmpty(this._userName))
            {
                e = "发件人账户名不能为空";
                return false;
            }
            if (string.IsNullOrEmpty(this._pwd))
            {
                e = "发件人密码不能为空";
                return false;
            }
            if (string.IsNullOrEmpty(this._smtp))
            {
                e = "smtp 地址不能为空";
                return false;
            }
            return true;
        }

        #endregion
    }
}