asp.net core 发送QQ邮件

.netframework 中发送邮件的api主要是使用SmtpClient 类，到了.netcore,官方并不推荐使用SmtpClient API，详情可查看官方说明:https://docs.microsoft.com/en-us/dotnet/api/system.net.mail.smtpclient?view=net-5.0,因此这里我使用第三方邮件发送库：MailKit 来进行邮件的发送。

配置QQ邮箱

• 登录QQ邮箱，选择设置->账户->POP3/IMAP/SMTP/Exchange/CardDAV/CalDAV服务
  
  开启POP3/SMTP服务以及IMAP/SMTP服务。

POP3服务开启流程
1.开启POP3服务![]
(https://www.lovecoding.com.cn:99//5596824483738550145.png)

2.POP3服务开启成功后如下图所示，会弹出一个框，注意：不是用这个框里的密码进行发送邮件

3.生成用于发送邮件的授权码

IMAP服务开启流程
开启流程和POP3开启流程类似。

创建邮件发送接口

• 安装nuget包MailKit
• 添加IMailService接口

  using System; using System.Collections.Generic; using System.Text; using System.Threading.Tasks;  namespace CommonLib.Email { 	public interface IMailService 	{ 		Task SendEmailAsync(MailRequest mailRequest); 	} } 

• 创建邮件信息相关实体类

  using Microsoft.AspNetCore.Http; using System; using System.Collections.Generic; using System.Text; namespace CommonLib.Email { 	public class MailRequest 	{ 		//收件地址 		public string ToEmail { get; set; } 		//邮件标题 		public string Subject { get; set; } 		//邮件内容,支持html 		public string Body { get; set; } 		//要发送的附件 		public List<IFormFile> Attachments { get; set; } 	} } 

• 创建邮箱配置信息实体类

  using System; using System.Collections.Generic; using System.Text; namespace CommonLib.Email { 	public class MailSettings 	{ 		//用于发送邮件的邮箱账号 		public string Mail { get; set; } 		//显示名称 		public string DisplayName { get; set; } 		//用于发送邮件的邮箱账号的授权码 		public string Password { get; set; } 		//用于发送邮件的邮箱服务器,QQ邮箱是：smtp.qq.com 		public string Host { get; set; } 		//用于发送邮件的邮箱服务器端口,QQ邮箱的端口是25 		public int Port { get; set; } 	} } 

• 创建实现具体邮件发送逻辑的类,并实现IMailService接口

  using MailKit.Net.Smtp; using MailKit.Security; using Microsoft.Extensions.Options; using MimeKit; using System; using System.Collections.Generic; using System.IO; using System.Text; using System.Threading.Tasks; namespace CommonLib.Email { 	public class MailService : IMailService 	{ 		private readonly MailSettings _mailSettings; 		public MailService(IOptions<MailSettings> mailSettings) 		{ 			_mailSettings = mailSettings.Value; 			//这里这个密码是QQ邮箱授权码 			_mailSettings.Password = mailSettings.Value.Password; 		} 		public async Task SendEmailAsync(MailRequest mailRequest) 		{ 			var email = new MimeMessage(); 			//一定要使用下面这句代码添加发送人邮箱信息,否则QQ收件箱那边无法看到发送人的邮箱信息。 			email.From.Add(MailboxAddress.Parse(_mailSettings.Mail)); 			email.Sender = MailboxAddress.Parse(_mailSettings.Mail); 			email.To.Add(MailboxAddress.Parse(mailRequest.ToEmail)); 			email.Subject = mailRequest.Subject; 			var builder = new BodyBuilder(); 			if (mailRequest.Attachments != null) 			{ 				byte[] fileBytes; 				foreach (var file in mailRequest.Attachments) 				{ 					if (file.Length > 0) 					{ 						using (var ms = new MemoryStream()) 						{ 							file.CopyTo(ms); 							fileBytes = ms.ToArray(); 						} 						builder.Attachments.Add(file.FileName, fileBytes, MimeKit.ContentType.Parse(file.ContentType)); 					} 				} 			} 			builder.HtmlBody = mailRequest.Body; 			email.Body = builder.ToMessageBody(); 			using (var smtp = new SmtpClient()) 			{ 				smtp.Connect(_mailSettings.Host, _mailSettings.Port, SecureSocketOptions.StartTls); 				smtp.Authenticate(_mailSettings.Mail, _mailSettings.Password); 				await smtp.SendAsync(email); 				smtp.Disconnect(true); 			} 		} 	} } 

打开appsettings.Development.json文件，加入发送邮件所用到的邮箱账号、邮箱服务器等信息。

{   "Logging": {     "LogLevel": {       "Default": "Information",       "Microsoft": "Warning",       "Microsoft.Hosting.Lifetime": "Information"     }   },   "MailSettings": {     "Mail": "[email protected]",     "DisplayName": "陈新",     "Password": "xxx",     "Host": "smtp.qq.com",     "Port": 25   },   "urls": "http://*:80" } 

到这里，基本配置工作已经完成，但是需要注意的是将代码发布到云服务器上（如腾讯云）时需要注意解封25端口，否则无法正常发送邮件。

腾讯云25端口开放方法请参见：https://cloud.tencent.com/document/product/213/40436