設計目標

• 靜態類別、屬性式配置，呼叫簡單：Email.Send()
• 支援：多收件人 (To/CC)、HTML 內文、多附件、SSL、自訂 SMTP Port
• 統一錯誤處理，回傳 bool 表示成敗

完整原始碼

using System;
using System.Net;
using System.Net.Mail;
using System.Text;

public static class Email
{
    // 寄件人
    public static string MailFrom { get; set; }
    // 收件人陣列
    public static string[] MailToArray { get; set; }
    // 副本陣列
    public static string[] MailCcArray { get; set; }
    // 主旨
    public static string MailSubject { get; set; }
    // 內文
    public static string MailBody { get; set; }
    // 寄件人密碼
    public static string MailPwd { get; set; }
    // SMTP 主機
    public static string Host { get; set; }
    // SMTP 埠
    public static int Port { get; set; }
    // 是否 HTML
    public static bool IsBodyHtml { get; set; }
    // 附件路徑陣列
    public static string[] AttachmentsPath { get; set; }

    public static bool Send()
    {
        try
        {
            var fromAddr = new MailAddress(MailFrom);
            var msg = new MailMessage { From = fromAddr };

            if (MailToArray != null)
                foreach (var to in MailToArray) msg.To.Add(to);
            if (MailCcArray != null)
                foreach (var cc in MailCcArray) msg.CC.Add(cc);

            msg.Subject = MailSubject;
            msg.SubjectEncoding = Encoding.UTF8;
            msg.Body = MailBody;
            msg.BodyEncoding = Encoding.Default;
            msg.Priority = MailPriority.High;
            msg.IsBodyHtml = IsBodyHtml;

            if (AttachmentsPath != null && AttachmentsPath.Length > 0)
            {
                foreach (var path in AttachmentsPath)
                    msg.Attachments.Add(new Attachment(path));
            }

            using (var client = new SmtpClient(Host, Port))
            {
                client.Credentials = new NetworkCredential(MailFrom, MailPwd);
                // client.EnableSsl = true; // 若需 SSL 取消註解
                client.Send(msg);
            }
            return true;
        }
        catch (SmtpException ex)
        {
            // 可記錄 ex.Message 至 Log
            return false;
        }
    }
}

使用範例

Email.MailFrom = "sender@example.com";
Email.MailPwd = "password";
Email.Host = "smtp.example.com";
Email.Port = 587;
Email.IsBodyHtml = true;
Email.MailToArray = new[] { "a@test.com", "b@test.com" };
Email.MailCcArray = new[] { "cc@test.com" };
Email.MailSubject = "測試郵件";
Email.MailBody = "
Hello
這是 HTML 郵件。
";
Email.AttachmentsPath = new[] { @"C:\report.pdf" };

bool ok = Email.Send();
Console.WriteLine(ok ? "發送成功" : "發送失敗");

常見問題與擴充

安全性提醒

• 勿將密碼硬編碼，建議從組態檔、Key Vault 或環境變數讀取。
• 生產環境務必啟用 SSL/TLS。
• 附件路徑驗證，防止路徑遍歷攻擊。