https://github.com/jstedfast/MailKit

https://github.com/jstedfast/MimeKit

https://www.cnblogs.com/pengze0902/p/6562447.html

public class EmailHelp    {        /// 
        /// Smtp服务器地址        /// 
        private static readonly string SmtpServer = ConfigurationManager.AppSettings["SmtpServer"];        /// 
        /// Pop服务器地址        /// 
        private static readonly string PopServer = ConfigurationManager.AppSettings["PopServer"];        /// 
        /// Imap服务器地址        /// 
        private static readonly string ImapServer = ConfigurationManager.AppSettings["ImapServer"];        /// 
        /// SMTP端口        /// 
        private static readonly int SmtpPort = int.Parse(ConfigurationManager.AppSettings["SmtpPort"]);        /// 
        /// POP端口        /// 
        private static readonly int PopPort = int.Parse(ConfigurationManager.AppSettings["PopPort"]);        /// 
        /// IMAP端口        /// 
        private static readonly int ImapPort = int.Parse(ConfigurationManager.AppSettings["ImapPort"]);        /// 
        /// 邮件发送        /// 
        /// 发送邮箱账号        /// 发送邮箱密码        /// 邮件        public static void SendEmali(string mailFromAccount, string mailPassword, MimeMessage message)        {            using (var client = new MailKit.Net.Smtp.SmtpClient())            {                client.Connect(SmtpServer, SmtpPort, false);                // Note: since we don't have an OAuth2 token, disable                // the XOAUTH2 authentication mechanism.                client.AuthenticationMechanisms.Remove("XOAUTH2");                // Note: only needed if the SMTP server requires authentication                client.Authenticate(mailFromAccount, mailPassword);                client.Send(message);                client.Disconnect(true);            }        }        /// 
        /// 创建文本消息        /// 
        /// 发件地址        /// 收件地址        /// 标题        /// 内容        /// 是否将POST上传文件加为附件        /// 
              public static MimeMessage CreateTextMessage(MailboxAddress fromAddress, IList
      
        toAddressList            , string title, string content, bool IsPostFiles = false)        {            var message = new MimeMessage();            message.From.Add(fromAddress);            message.To.AddRange(toAddressList);            message.Subject = title; //设置消息的主题            var html = new TextPart("html")            {                Text = content,            };            var alternative = new Multipart("alternative");            alternative.Add(html);            var multipart = new Multipart("mixed");            multipart.Add(alternative);            if (IsPostFiles)            {                IList
       
         multiPartList = GetMimePartList();                foreach (var item in multiPartList)                {                    multipart.Add(item);                }            }            message.Body = multipart;            return message;        }        /// 
        
        /// 收邮件        /// 
        /// 
        发送邮箱账号        /// 
        发送邮箱密码        /// 
        查询条件        /// 
        文件夹名称        /// 
                public static IList
        
          ReceiveEmail(string mailFromAccount, string mailPassword, string folderName, SearchQuery searchQuery = null)        {            //打开收件箱            var folder = OpenFolder(mailFromAccount, mailPassword, folderName);            //IList
         
           orderByList = new List
          
            { OrderBy.Date };            //查询所有的邮件            var uidss = folder.Search(searchQuery);            IList
           
             msgList = new List
            
             (); if (uidss.Count > 0)//判断是否查询到邮件 { //获取邮件头 msgList = folder.Fetch(uidss, MessageSummaryItems.UniqueId | MessageSummaryItems.Full); } folder.Close(); return msgList; } /// 
             
 /// 根据唯一号查询信件 /// 
 /// 
             邮箱账号 /// 
             邮箱密码 /// 
             唯一号 /// 
             文件夹名称 /// 
              public static MimeMessage GetEmailByUniqueId(string mailFromAccount, string mailPassword, uint id, string folderName) { //打开收件箱 var folder = OpenFolder(mailFromAccount, mailPassword, folderName); UniqueId emailUniqueId = new UniqueId(id); MimeMessage message = folder.GetMessage(emailUniqueId); /*将邮件设为已读*/ MessageFlags flags = MessageFlags.Seen; folder.SetFlags(emailUniqueId, flags, true); return message; } /// 
             
 /// 读取上传的文件 /// 
 /// 
              public static IList
             
               GetMimePartList() { IList
              
                mimePartList = new List
               
                (); var current = HttpContext.Current; if (current != null) { HttpRequest request = current.Request; HttpFileCollection files = request.Files; int filesCount = files.Count; for (int i = 0; i < filesCount; i++) { HttpPostedFile item = files[i]; MimePart attachment = new MimePart(item.ContentType) { ContentObject = new ContentObject(item.InputStream, ContentEncoding.Default), ContentDisposition = new ContentDisposition(ContentDisposition.Attachment), ContentTransferEncoding = ContentEncoding.Base64, FileName = item.FileName }; mimePartList.Add(attachment); } } return mimePartList; } /// 
                
 /// 打开邮箱文件夹 /// 
 /// 
                邮箱账号 /// 
                邮箱密码 /// 
                文件夹名称(INBOX:收件箱名称) /// 
                 public static IMailFolder OpenFolder(string mailFromAccount, string mailPassword, string folderName) { ImapClient client = new ImapClient(); client.Connect(ImapServer, ImapPort); client.Authenticate(mailFromAccount, mailPassword); //获取所有文件夹 //List
                
                  mailFolderList = client.GetFolders(client.PersonalNamespaces[0]).ToList(); var folder = client.GetFolder(folderName); //打开文件夹并设置为读的方式 folder.Open(MailKit.FolderAccess.ReadWrite); return folder; } /// 
                 
 /// 下载邮件附件 /// 
 /// 
                  public static void DownFile(MimePart mimePart) { HttpContext context = HttpContext.Current; // 设置编码和附件格式 context.Response.ContentType = mimePart.ContentType.ToString(); //context.Response.ContentEncoding = Encoding.UTF8; context.Response.Charset = ""; string fileName = HttpUtility.UrlEncode(mimePart.FileName, Encoding.UTF8); context.Response.AppendHeader("Content-Disposition", "attachment;filename=" + fileName); using (MemoryStream ms = new MemoryStream()) { mimePart.ContentObject.DecodeTo(ms); ms.Flush(); ms.Position = 0; context.Response.BinaryWrite(ms.GetBuffer()); context.Response.End(); } } }
                
               
              
             
            
           
          
         
        
       
      

http://www.mimekit.net/

MailKit正式替换了.NET的SmtpClient

SmtpClient的文档现已改成：“废弃（“SmtpClient及其相关类型设计很差，我们强烈建议使用和替代。”）”。这是Microsoft有史以来第二次将一个.NET类正式标为被开源软件库替代。

和的创建者是Jeffrey Stedfast，InfoQ曾在。在当时，它们已被认为是.NET上最全面的MIME和电子邮件库。

是被Microsoft接受的首个重要开源库。JSON.NET已在ASP.NET Web API中广泛使用，并被正式推荐为Web API使用的序列化类，通常可替代类。但是不同于SmtpClient的是，没有任何一个序列化类因此被标记为废弃。

client.Inbox.Open (FolderAccess.ReadOnly);var uids = client.Inbox.Search (SearchQuery.SubjectContains ("HELLO_"));if (uids.Count > 0) {    var summaries = client.Inbox.Fetch (uids, MessageSummaryItems.Envelope);    foreach (var summary in summaries) {        if (summary.Envelope.Subject.StartsWith ("HELLO_"))            return summary.Envelope.Subject;    }}