【.Net 6.0--通用帮助类--EmailHelper】

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）

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; }
    }
}