C#发送邮件，包含发送附件

/// 

/// 发送邮件
/// 
/// 收件人邮箱
/// 发件人邮箱
/// 发件人名称
/// 邮件标题
/// 邮件内容
/// 抄送人邮箱
public static void SendEmail(string sendEmail, string fromEmail, string fromName, string title, string body, List sendCC)
{
    MailMessage msg = new MailMessage();

    msg.To.Add(sendEmail); //收件人邮箱
    msg.From = new MailAddress(fromEmail, fromName);  //发件人邮箱和名称
    msg.Subject = title;//邮件标题 
    msg.SubjectEncoding = Encoding.UTF8; //邮件标题格式为UTF8 
    msg.Body = body;//邮件内容
    msg.BodyEncoding = Encoding.UTF8; //邮件内容格式为UTF8 
    msg.IsBodyHtml = true;//设置邮件格式为html格式
    //设置抄送人地址
    if (sendCC != null && sendCC.Count > 0)
    {
        foreach (String cc in sendCC)
        {
            msg.CC.Add(cc);
        }
    }
    //添加附件
    //string filePath = @"C:\附件.xls";
    //msg.Attachments.Add(new Attachment(filePath));

    SmtpClient client = new SmtpClient();

    client.Host = "smtp.qq.com"; //SMTP服务器地址 
    client.Port = 587; //SMTP端口，QQ邮箱填写587 
    client.EnableSsl = true; //启用SSL加密 （使用除QQ邮箱之外的最好关闭）
    client.Credentials = new System.Net.NetworkCredential(fromEmail, "xxxxxxxxxxx"); //发件人邮箱账号，授权码（不是密码）
    try
    {
        client.Send(msg); //发送邮件
    }
    catch (Exception)
    {
        throw;
    }
}

注意：如果使用qq邮箱，密码请从邮箱中获取，如下图
设置 => 账号 => POP3/IMAP/SMTP/Exchange/CardDAV/CalDAV