一、基本概念
在C#编程环境中，实现邮件发送功能是一项常见的需求，无论是Web应用程序还是Windows窗体应用程序，邮件服务都能帮助用户进行信息的传递和沟通。使用C#中的System.Net库，来实现自动发送邮件的功能。
二、邮箱授权
下面进行邮箱的授权，本篇文章使用QQ邮箱作为案列进行示范。
发送完成按照指引将会获得一串授权码。将授权码填入下面代码的指定位置。
三、示例代码
使用System.Net.Mail发送一封简单的文本邮件：
using System;
using System.Net;
using System.Net.Mail;class EmailSender
{public static void Main(){try{// 配置SMTP服务器信息（以QQ邮箱为例）string smtpServer = "smtp.qq.com"; //此处修改发送邮箱的服务器地址int smtpPort = 587;bool enableSsl = true;string fromEmail = "your_email@qq.com";//使用的邮箱string password = "your_password_or_auth_code"; // 此处填写刚刚获得的授权码// 创建邮件客户端using SmtpClient client = new SmtpClient(smtpServer){Port = smtpPort,Credentials = new NetworkCredential(fromEmail, password),EnableSsl = enableSsl};// 创建邮件内容MailMessage message = new MailMessage{From = new MailAddress(fromEmail),Subject = "测试邮件",Body = "这是一封来自C#程序的测试邮件",IsBodyHtml = false // 设置为true发送HTML邮件};// 添加收件人message.To.Add("recipient@example.com"); //填入接受邮件的邮箱地址// 发送邮件client.Send(message);Console.WriteLine("邮件发送成功！");}catch (Exception ex){Console.WriteLine($"邮件发送失败：{ex.Message}");}}
}常见邮箱服务器配置
| 邮箱服务商 | SMTP服务器地址 | 端口 | SSL要求 |
|---|---|---|---|
| QQ邮箱 | smtp.qq.com | 587 | 是 |
| 163邮箱 | smtp.163.com | 465 | 是 |
| Gmail | smtp.gmail.com | 587 | 是 |
| Outlook | smtp.office365.com | 587 | 是 |
四、制作一个报错提醒功能的函数
制作一个报错提醒功能的函数，当现成的程序出现了问题，自动发送邮件提醒程序员进行远程处理。打工的牛马制作一个鞭子抽自己起来干活。实现效果如下
using System;
using System.Diagnostics;
using System.Net;
using System.Net.Mail;
using System.Security.Cryptography;
using System.Text;class EmailSender
{// ======== 配置信息 ========static string smtpServer = "smtp.qq.com";static int smtpPort = 587;static bool enableSsl = true;static string fromEmail = "填入发送的邮箱"; //发送邮箱static string password = "邮箱授权码"; // QQ邮箱需要授权码static string incomingEmail = "接受邮件的邮箱地址";//收件邮箱地址 private static readonly object fileLock = new object();private const string LogDirectory = "EmailSendLogs";/// <summary>/// 报警信息发送至邮箱/// </summary>/// <param name="alertLevel">报警级别支持： /// CRITICAL：严重问题（红色）/// HIGH：高级别问题（橙色）/// MEDIUM：中等问题（黄色）/// LOW：低级别通知（绿色）/// </param>/// <param name="alertContent">报警内容</param>/// <param name="errorDetails">错误详情</param>/// <param name="attachmentPaths">附件</param>public static void SendToEmail(string alertLevel, string alertContent, string errorDetails = null, string[] attachmentPaths = null){try{//1和2是会在程序运行的文件夹中生成一个日志文件，当同一个报错今天已经发送过了，将会 //不再发送，防止报错一直触发然后一直给自己发送邮件，这样子抽牛马干活打在自己身上就太痛了// ===== 1. 生成错误唯一标识 =====string errorHash = GenerateErrorHash(alertContent, errorDetails);// ===== 2. 检查是否已发送过 =====if (IsAlreadySentToday(errorHash)){Console.WriteLine("相同错误今日已发送过，不再重复发送");return;}// ======== 创建邮件客户端 ========using SmtpClient client = new SmtpClient(smtpServer){Port = smtpPort,Credentials = new NetworkCredential(fromEmail, password),EnableSsl = enableSsl};// ======== 报警级别颜色映射 ========var alertLevelInfo = new Dictionary<string, (string color, string emoji)>{{ "CRITICAL", ("#d32f2f", "🔥") }, // 红色{ "HIGH", ("#f57c00", "⚠️") }, // 橙色{ "MEDIUM", ("#ffa000", "❗") }, // 黄色{ "LOW", ("#4caf50", "ℹ️") } // 绿色};// 获取当前报警级别的颜色和表情符号var (color, emoji) = alertLevelInfo.ContainsKey(alertLevel)? alertLevelInfo[alertLevel]: ("#666666", "🔔");// ======== 构建邮件内容 ========string htmlBody = $@"<!DOCTYPE html><html><head><style>.card {{ border: 1px solid #e0e0e0; padding: 20px; max-width: 800px;font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;}}.header {{ border-bottom: 2px solid {color};padding-bottom: 10px;margin-bottom: 20px;}}.alert-level {{ color: {color};font-weight: bold;}}pre {{background: #f8f9fa;padding: 15px;border-radius: 4px;overflow-x: auto;}}</style></head><body><div class='card'><div class='header'><h2>{emoji} 系统报警 - {alertLevel}</h2></div><table><tr><th>报警时间:</th><td>{DateTime.Now:yyyy-MM-dd HH:mm:ss}</td></tr><tr><th>报警级别:</th><td class='alert-level'>{alertLevel}</td></tr></table><h3>▌ 报警内容</h3><p>{alertContent}</p>{(errorDetails != null ? $@"<h3>▌ 错误详情</h3><pre>{errorDetails}</pre>" : "")}<div style='margin-top: 25px; color: #666; font-size: 0.9em;'><hr><p>此邮件由系统自动发送，请勿直接回复</p><p>负责人：牛马程序员 (123456@niuma.com)</p></div></div></body></html>";// ======== 创建邮件消息 ========MailMessage message = new MailMessage{From = new MailAddress(fromEmail),Subject = $"{emoji} 系统报警 - {alertLevel}",Body = htmlBody,IsBodyHtml = true};// 添加收件人message.To.Add(incomingEmail);// 添加附件if (attachmentPaths != null){foreach (var path in attachmentPaths){if (File.Exists(path)){message.Attachments.Add(new Attachment(path));}}}// ======== 发送邮件 ========client.Send(message);// ===== 4. 记录发送日志 =====LogError(errorHash, alertLevel, alertContent, errorDetails);Console.WriteLine("邮件发送成功！");}catch (Exception ex){Console.WriteLine($"邮件发送失败：{ex.Message}");}}/// <summary>/// 创建唯一加密标识符号/// </summary>/// <param name="content"></param>/// <param name="details"></param>/// <returns></returns>private static string GenerateErrorHash(string content, string details){using MD5 md5 = MD5.Create();string rawData = $"{content}|{details}";byte[] hashBytes = md5.ComputeHash(Encoding.UTF8.GetBytes(rawData));return BitConverter.ToString(hashBytes).Replace("-", "");}/// <summary>/// 检查是否已经发送过/// </summary>/// <param name="errorHash"></param>/// <returns></returns>private static bool IsAlreadySentToday(string errorHash){string todayLogFile = GetTodayLogFilePath();lock (fileLock){if (!File.Exists(todayLogFile)) return false;foreach (string line in File.ReadAllLines(todayLogFile)){if (line.StartsWith(errorHash)){return true;}}}return false;}//记录报警内容private static void LogError(string errorHash, string level,string content, string details){string logEntry = $"{errorHash}|{DateTime.Now:yyyy-MM-dd HH:mm:ss}|" +$"{level}|{content}|{details}\n";lock (fileLock){EnsureLogDirectoryExists();File.AppendAllText(GetTodayLogFilePath(), logEntry);}}//获取报警日志地址private static string GetTodayLogFilePath(){return Path.Combine(LogDirectory,$"SnedErrorLog_{DateTime.Now:yyyyMMdd}.txt");}//无文件创建文件夹private static void EnsureLogDirectoryExists(){if (!Directory.Exists(LogDirectory)){Directory.CreateDirectory(LogDirectory);}}public static void Main(){SendToEmail(alertLevel: "HIGH",alertContent: "数据库益处请处理，可能导致系统响应缓慢。",errorDetails: "TimeoutException: Could not connect to database.\n at DatabaseService.Connect() Line 123",attachmentPaths: new[] { "error.log" });SendToEmail(alertLevel: "HIGH",alertContent: "数据库连接池使用率超过90%，可能导致系统响应缓慢。",errorDetails: "TimeoutException: Could not connect to database.\n at DatabaseService.Connect() Line 123",attachmentPaths: new[] { "error.log" });}
}