准备将一些项目迁移到 asp.net core 先从封装类库入手，在遇到邮件发送类时发现在 asp.net core 1.0中并示提供SMTP相关类库，于是网上一搜发现了MailKit
好东西一定要试一下，何况是开源，下面是代码可实现SMTP邮件发送：
using MailKit.Net.Smtp;
using MailKit.Security;
using MimeKit;
using System.Threading.Tasks;
namespace ConsoleApp1
{
public class MailHelper
{
public static void Send(string email, string subject, string message)
{
var emailMessage = new MimeMessage();
emailMessage.From.Add(new MailboxAddress("tianwei blogs", "mail@linuxidc.com"));
emailMessage.To.Add(new MailboxAddress("mail", email));
emailMessage.Subject = subject;
emailMessage.Body = new TextPart("plain") { Text = message };
using (var client = new SmtpClient())
{
client.Connect("smtp.linuxidc.com", 465, true);
client.Authenticate("mail@linuxidc.com", "******");
client.Send(emailMessage);
client.Disconnect(true);
}
}
public static async Task SendEmailAsync(string email, string subject, string message)
{
var emailMessage = new MimeMessage();
emailMessage.From.Add(new MailboxAddress("tianwei blogs", "mail@linuxidc.com"));
emailMessage.To.Add(new MailboxAddress("mail", email));
emailMessage.Subject = subject;
emailMessage.Body = new TextPart("plain") { Text = message };
using (var client = new SmtpClient())
{
await client.ConnectAsync("smtp.linuxidc.com", 25, SecureSocketOptions.None).ConfigureAwait(false);
await client.AuthenticateAsync("mail@linuxidc.com", "******");
await client.SendAsync(emailMessage).ConfigureAwait(false);
await client.DisconnectAsync(true).ConfigureAwait(false);
}
}
}
}
以上代码同步异步都没有问题
注：一般邮箱如腾讯企业邮、163等都可以发送成功，但阿里云邮件推送失败！
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用MailKit实现了Asp.net core 邮件发送功能，但一直未解决阿里云邮件推送问题，提交工单一开始的回复不尽如人意，比如您的网络问题，您的用户名密码不正确等，但继续沟通下阿里云客户还是很耐心的。
最终结论，是由于MailKit发送了两次EHLO命令，查看了MailKit源码后竟然发现，里面写了硬编码：
if (host != "smtp.strato.de" && host != "smtp.sina.com") Ehlo (cancellationToken); authenticated = true; OnAuthenticated (response.Response);
哈哈，只要把阿里云SMTP地址加上就好：smtpdm.aliyun.com