前言

邮件帮助类（smtp协议），需要NuGet引用MailKit包，包含了同步发送邮件（SendEmail)、异步发送邮件（ SendEmailAsync）方法，由于非企业邮箱每日有发送限额，故代码中支持轮询多个邮箱，当某个邮箱超限时，标记为不可用状态，当天不再使用，以确保邮件正常发送成功，同时支持多种邮箱类型，见下表。

下表为常用邮箱服务器的地址和端口（SMTP/POP）

邮箱类型	SMTP-服务器地址	SMTP-端口号	POP-服务器地址	POP-端口号	是否SSL
163邮箱	smtp.163.com	25	pop.163.com	110	否
126邮箱	smtp.126.com	25	pop.126.com	110	否
139邮箱	smtp.139.com	25	pop.139.com	110	否
QQ邮箱	smtp.qq.com	25	pop.qq.com	110	否
QQ企业邮箱	smtp.exmail.qq.com	587/465	pop.exmail.qq.com	995	是
Gmail邮箱	smtp.gmail.com	587	pop.gmail.com	995	是
Foxmail邮箱	smtp.foxmail.com	25	pop.foxmail.com	110	否
Sina邮箱	smtp.sina.com.cn	25	pop3.sina.com.cn	110	否
SinaVIP邮箱	smtp.vip.sina.com	25	pop3.vip.sina.com	110	否
Sohu邮箱	smtp.sohu.com	25	pop3.sohu.com	110	否
Yahoo邮箱	smtp.mail.yahoo.com.cn	587	pop.mail.yahoo.com.cn	995	是

代码中的email.json格式如下，请自行配置个人邮箱：

[{"Host": "smtp.163.com","EnableSsl": true,"Port": 465,"SendAddress": "xxxx@163.com","LoginPassword": "邮箱登录密码","Password": "smtp分配的密码，代码中使用此密码","CanUse": true}
]

---

代码示例

using MailKit.Net.Smtp;
using MimeKit;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using VW.API.Common.Models;namespace VW.API.Common.Utils
{/// <summary>/// EmailHelper 的摘要说明：邮件帮助类/// </summary>public class EmailHelper{private static readonly string _emailConfigPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Configs/email.json");/// <summary>/// 创建Email/// </summary>/// <param name="email">邮箱地址</param>/// <param name="subject">邮件主题</param>/// <param name="message">邮件内容</param>/// <param name="attachments">附件</param>/// <returns>Email</returns>private static SmtpClient GetSmtpClient(string email, string subject, string message, List<string> attachments, EmailModel emailModel, out MimeMessage mimeMessage){try{var client = new SmtpClient();client.MessageSent += (sender, args) =>{LogHelper.Error(args.Message.ToString());};client.ServerCertificateValidationCallback = (sender, certificate, certChainType, errors) => true;client.Connect(emailModel.Host, emailModel.Port, emailModel.EnableSsl);client.Authenticate(emailModel.SendAddress, emailModel.Password);mimeMessage = new MimeMessage();mimeMessage.From.Add(new MailboxAddress(emailModel.SendAddress, emailModel.SendAddress));mimeMessage.To.Add(new MailboxAddress(email, email));mimeMessage.Subject = subject;var builder = new BodyBuilder();builder.HtmlBody = message;foreach (var attachment in attachments){builder.Attachments.Add(attachment);}mimeMessage.Body = builder.ToMessageBody();return client;}catch (Exception) { throw; }}/// <summary>/// 发送邮件（同步）/// </summary>/// <param name="email">邮箱地址</param>/// <param name="subject">邮件主题</param>/// <param name="message">邮件内容</param>/// <param name="attachments">附件</param>/// <returns>bool</returns>public static bool SendEmail(string email, string subject, string message, List<string> attachments = null){bool success = false;string lastDayFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, $"Configs/{DateTime.Now.AddDays(-1).ObjToDateSplitYMD()}.email.json");FileHelper.DeleteFile(lastDayFilePath);string todayFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, $"Configs/{DateTime.Now.ObjToDateSplitYMD()}.email.json");if (!FileHelper.IsExistFile(todayFilePath))FileHelper.Copy(_emailConfigPath, todayFilePath, true);List<EmailModel> emailModels = JsonConvert.DeserializeObject<List<EmailModel>>(FileHelper.FileToString(todayFilePath));foreach (EmailModel emailModel in emailModels){if (!emailModel.CanUse)//不能使用continue;try{var client = GetSmtpClient(email, subject, message, attachments, emailModel, out MimeMessage mimeMessage);client.Send(mimeMessage);client.Disconnect(true);//client.Dispose();success = true;break;}catch (Exception ex){LogHelper.Error(JsonConvert.SerializeObject(emailModel));LogHelper.Error(ex.ToString());emailModel.CanUse = false;success = false;}}FileHelper.WriteText(todayFilePath, JsonConvert.SerializeObject(emailModels));return success;}/// <summary>/// 发送邮件（异步）/// </summary>/// <param name="email">邮箱地址</param>/// <param name="subject">邮件主题</param>/// <param name="message">邮件内容</param>/// <param name="attachments">附件</param>/// <returns>bool</returns>public static async Task<bool> SendEmailAsync(string email, string subject, string message, List<string> attachments){bool success = false;string lastDayFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, $"Configs/{DateTime.Now.AddDays(-1).ObjToDateSplitYMD()}.email.json");FileHelper.DeleteFile(lastDayFilePath);string todayFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, $"Configs/{DateTime.Now.ObjToDateSplitYMD()}.email.json");if (!FileHelper.IsExistFile(todayFilePath))FileHelper.Copy(_emailConfigPath, todayFilePath, true);List<EmailModel> emailModels = JsonConvert.DeserializeObject<List<EmailModel>>(FileHelper.FileToString(todayFilePath));foreach (EmailModel emailModel in emailModels){if (!emailModel.CanUse)//不能使用continue;try{var client = GetSmtpClient(email, subject, message, attachments, emailModel, out MimeMessage mimeMessage);await client.SendAsync(mimeMessage);client.Disconnect(true);//client.Dispose();success = true;break;}catch (Exception ex){LogHelper.Error(JsonConvert.SerializeObject(emailModel));LogHelper.Error(ex.ToString());emailModel.CanUse = false;success = false;}}FileHelper.WriteText(todayFilePath, JsonConvert.SerializeObject(emailModels));return success;}}
}

namespace VW.API.Common.Models
{/// <summary>/// EmailModel/// </summary>public class EmailModel{/// <summary>/// 主机地址/// </summary>public string Host { set; get; }/// <summary>/// 是否使用SSL/// </summary>public bool EnableSsl { set; get; }/// <summary>/// 端口号/// </summary>public int Port { set; get; }/// <summary>/// 邮件地址/// </summary>public string SendAddress { set; get; }/// <summary>/// 登录密码/// </summary>public string LoginPassword { set; get; }/// <summary>/// 邮件STMP授权码/// </summary>public string Password { set; get; }/// <summary>/// 是否可用/// </summary>public bool CanUse { set; get; }}
}