使用 MimeKit 和 MailKit 发送邮件

MimeKit 给.NET 社区带来了一流的 MIME 解析器，它能处理复杂的各种Mime， 性能好。而且开箱即用支持 S/MIME 和 PGP。MimeKit 和 MailKit 支持最新的国际化的电子邮件标准，是.NET 中为一个支持完整支持这些标准电子邮件库，最近正式发布了1.0版本。如果你想做所有与的电子邮件相关的事情，看看 MimeKit 和 MailKit。我保证你不会失望，它支持.NET/Mono的所有平台，包括移动电话、平板等。

使用方法很简单和.NET的SmtpClient 差不多，不过比它优雅多了，下面show个代码：

using MimeKit;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Mail;
using System.Text;
using System.Threading.Tasks;
using MailKit.Net.Smtp;
using System.IO;

namespace NetSmtpClient
{
    class Program
    {
        const string mailFrom = "xxxx@hotmail.com";
        const string mailTo = "xxxx@qq.com";
        const string mailFromAccount = "xxxx@hotmail.com";
        const string mailPassword = "xxxx";
        const string path = @"E:\GitHub\TestMailClient\NetSmtpClient\.NETFoundation.png";
        static void Main(string[] args)
        {
            TestSmtpClient();

            TestMailKit();

        }

        private static void TestMailKit()
        {
            var message = new MimeMessage();
            message.From.Add(new MailboxAddress("geffzhang", mailFrom));
            message.To.Add(new MailboxAddress("geffzhang", mailTo));
            message.Subject = string.Format("C#自动发送邮件测试 From geffzhang TO {0}", mailTo);

            var plain = new TextPart("plain")
            {
                Text = @"不好意思，我在测试程序，刚才把QQ号写错了，Sorry！"
            };
            var html = new TextPart("html")
            {
                Text = @"<p>Hey geffzhang<br>
<p>不好意思，我在测试程序，刚才把QQ号写错了，Sorry！<br>
<p>-- Geffzhang<br>"
            };
            // create an image attachment for the file located at path
            var attachment = new MimePart("image", "png")
            {
                ContentObject = new ContentObject(File.OpenRead(path), ContentEncoding.Default),
                ContentDisposition = new ContentDisposition(ContentDisposition.Attachment),
                ContentTransferEncoding = ContentEncoding.Base64,
                FileName = Path.GetFileName(path)
            };

            var alternative = new Multipart("alternative");
            alternative.Add(plain);
            alternative.Add(html);

            // now create the multipart/mixed container to hold the message text and the
            // image attachment
            var multipart = new Multipart("mixed");
            multipart.Add(alternative);
            multipart.Add(attachment);
            message.Body = multipart;

            using (var client = new MailKit.Net.Smtp.SmtpClient())
            {
                client.Connect("smtp.live.com", 587, 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);
            }
        }

        private static void TestSmtpClient()
        {
            MailMessage mymail = new MailMessage();
            mymail.From = new System.Net.Mail.MailAddress(mailFrom);
            mymail.To.Add(mailTo);
            mymail.Subject = string.Format("C#自动发送邮件测试 From geffzhang TO {0}",mailTo);
            mymail.Body = @"<p>Hey geffzhang<br><p>不好意思，我在测试程序，刚才把QQ号写错了，Sorry！<br><p>-- Geffzhang<br>";
            mymail.IsBodyHtml = true;
            mymail.Attachments.Add(new Attachment(path));

            System.Net.Mail.SmtpClient smtpclient = new System.Net.Mail.SmtpClient();
            smtpclient.Port = 587;
            smtpclient.UseDefaultCredentials = false;
            smtpclient.DeliveryMethod = SmtpDeliveryMethod.Network;
            smtpclient.Host = "smtp.live.com";
            smtpclient.EnableSsl = true;
            smtpclient.Credentials = new System.Net.NetworkCredential(mailFromAccount, mailPassword);
            try
            {
                smtpclient.Send(mymail);
                Console.WriteLine("发送成功");

            }
            catch (Exception ex)
            {
                Console.WriteLine("发送邮件失败.请检查是否为qq邮箱，并且没有被防护软件拦截" + ex);

            }
        }
    }
}

上面代码是smtp发送代码，这个库还支持POP3, 和 IMAP 等。