AspNetCore 目前不支持SMTP协议（基于开源组件开发邮件发送，它们分别是MailKit 和 FluentEmail ）

net所有的功能都要重新来一遍，集成众多类库，core任重道远，且发展且努力!!

我们都知道，很多的邮件发送都是基于这个SMTP协议，但现在的.net core对这方面还不太支持，所以我们选择这两个组件MailKit 和 FluentEmail

MailKit与fluentEmail

在 ASP.NET Core 中，可以使用 MailKit 来发送邮件，它支持跨平台，并且支持 IMAP, POP3, SMTP 等协议。

你可以使用下面的方式安装：

Install-Package MailKit

直接show代码吧！！

using MimeKit;
using System;
using System.IO;

namespace SMTP协议
{
    class Program
    {
        static void Main(string[] args)
        {
            TestSendMailDemo();
        }
        public static void TestSendMailDemo()
        {
            var message = new MimeKit.MimeMessage();
            message.From.Add(new MimeKit.MailboxAddress("zara", "947099752@qq.com"));
            message.To.Add(new MimeKit.MailboxAddress("zaranet", "zaranet@163.com"));
            message.Subject = "This is a Test Mail";
            var plain = new MimeKit.TextPart("plain")
            {
                Text = @"不好意思，我在测试程序，Sorry！"
            };
            var html = new MimeKit.TextPart("html")
            {
                Text = @"<p>Hey geffzhang<br>
                        <p>不好意思，我在测试程序，Sorry！<br>
                        <p>-- Geffzhang<br>"
            };
            // create an image attachment for the file located at path
            var path = @"C:\Users\MACHENIKE\Desktop\a.png";
            var fs = File.OpenRead(path);
            var attachment = new MimeKit.MimePart("image", "jpeg")
            {

                ContentObject = new MimeKit.ContentObject(fs, MimeKit.ContentEncoding.Default),
                ContentDisposition = new MimeKit.ContentDisposition(MimeKit.ContentDisposition.Attachment),
                ContentTransferEncoding = MimeKit.ContentEncoding.Base64,
                FileName = Path.GetFileName(path)
            };
            var alternative = new MimeKit.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 MimeKit.Multipart("mixed");
            multipart.Add(alternative);
            multipart.Add(attachment);
            message.Body = multipart;
            using (var client = new MailKit.Net.Smtp.SmtpClient())
            {
                client.Connect("smtp.qq.com", 465, true);

                // 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
                var mailFromAccount = "947099752@qq.com";
                var mailPassword = "xxxx";
                client.Authenticate(mailFromAccount, mailPassword);
                client.Send(message);
                client.Disconnect(true);
            }
            fs.Dispose();
        }
    }
}

结果：

BUG::　　

1.其中通过mailkit发送的时候  发送方必须要打开自己的POP3/IMAP/SMTP/Exchange/CardDAV/CalDAV服务 一般是在自己的个人中心   2018-11-12  16:11:41

2.一般来说授权码是在个人中心，而且一定有帮助 里面有关于他的服务什么的

FluentEmail 

　　

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);

            }
        }
    }