EDM开发之二：SMTP服务器

SMTP服务器

服务器的搭建我就不做过多的叙述了，网上有很多，这里主要讲一下SMTP的工作原理和工作过程。

SMTP通常有两种工作模式：发送SMTP和接收SMTP。具体工作方式为：发送SMTP在接到用户的邮件请求后，判断此邮件是否为本地邮件，若是直接投送到用户的邮箱，否则向dns查询远端邮件服务器的MX纪录，并建立与远端接收SMTP之间的一个双向传送通道，此后SMTP命令由发送SMTP发出，由接收SMTP接收，而应答则反方面传送。一旦传送通道建立，SMTP发送者发送MAIL命令指明邮件发送者。如果SMTP接收者可以接收邮件则返回OK应答。SMTP发送者再发出RCPT命令确认邮件是否接收到。如果SMTP接收者接收，则返回OK应答；如果不能接收到，则发出拒绝接收应答（但不中止整个邮件操作），双方将如此重复多次。当接收者收到全部邮件后会接收到特别的序列，如果接收者成功处理了邮件，则返回OK应答即可。

下面是我个人对邮件在SMTP服务器文件夹中的旅行路径，如有错误请指正：

邮件发送分为同步发送和异步发送：

/// <summary>
/// 邮件设置
/// </summary>
/// <param name="toAddress">收件人地址</param>
/// <param name="fromAddress">发件人地址</param>
/// <param name="toName">收件人名字</param>
/// <param name="fromName">发件人姓名</param>
/// <param name="title">主题</param>
/// <param name="body">正文</param>
/// <param name="isBodyHtml">正文是否为html格式</param>
public SendEmail(string toAddress, string fromAddress, string toName, string fromName, string title, string body, bool isBodyHtml)
{
    mailMessage.From = new MailAddress(fromAddress, fromName, Encoding.GetEncoding(936));
    if (toName.Equals(""))
        mailMessage.To.Add(toAddress);
    else
        mailMessage.To.Add(new MailAddress(toAddress, toName, Encoding.GetEncoding(936)));

    mailMessage.Subject = title;
    mailMessage.SubjectEncoding = Encoding.GetEncoding(936);

    mailMessage.Body = body;
    mailMessage.IsBodyHtml = isBodyHtml;
    mailMessage.BodyEncoding = Encoding.GetEncoding(936);
}
/// <summary>
/// 设置SMTP，并且将邮件发送出去
/// 所有参数都设置完成后再调用该方法
/// </summary>
/// <param name="address">发件人地址（必须为真实有效的email地址）</param>
/// <param name="password">发件人密码</param>
/// <param name="smtpHost">SMTP服务器地址，例如：smtp.163.com</param>
/// <param name="smtpPort">SMTP服务器的端口，一般为25</param>
/// <param name="isEnableSsl">SMTP服务器是否启用SSL加密</param>
/// <param name="priority">邮件的优先级</param>
/// <param name="UseDefaultCredentials">设置是否需要身份验证</param>
public void SetSmtp(string address, string password, string smtpHost, int smtpPort, bool isEnableSsl, MailPriority priority)
{
    var smtp = new SmtpClient
    {
        DeliveryMethod = SmtpDeliveryMethod.Network,//电子邮件通过网络发送到SMTP服务器
        Credentials = new NetworkCredential(address, password),
        Host = smtpHost,
        Port = smtpPort,
        UseDefaultCredentials = true,
        EnableSsl = isEnableSsl
    };
    mailMessage.Priority = priority;
    //smtp.Send(mailMessage); //同步发送邮件
    smtp.SendAsync(mailMessage, mailMessage.To.ToString());//异步发送邮件
}

除非检测SMTP的log日志文件，否则我们并不知道邮件是否发送成功，检测SMTP日志可以用logparser工具，他可以像sql那样通过查询语句来获得log的日志内容：

net start smtpsvc /启动smtp日志记录命令行/

using LogQuery = MSUtil.LogQueryClass;
using LogRecordSet = MSUtil.ILogRecordset;
using TsvInputFormat = MSUtil.COMTSVInputContextClass;
public class LogParser
{
    /// <summary>      
    /// 计算日志条数    
    /// </summary>      
    public double GetLogCount(string headerFile, string logName)
    {
        double avgLockSec = 0;
        var oLogQuery = new LogQuery();
        var oTsvInputFormat = new TsvInputFormat { iHeaderFile = headerFile };
        string query = "select * from '" + logName + "'";
        LogRecordSet oRecordSet = oLogQuery.Execute(query, oTsvInputFormat);
        if (!oRecordSet.atEnd())
        {
            double item = 0;
            if (!oRecordSet.getRecord().isNull(0))
            {
                item = double.Parse(oRecordSet.getRecord().getValue(0).ToString());
            }
            avgLockSec = item;
        }
        oRecordSet.close();
        return avgLockSec;
    }
}

根据上面图片我们知道，发送失败的Email会放到Drop和BadEmail两个文件夹中，所以只要监测两个文件夹，有文件进来就是发送失败的邮件：

public static class MyFileSystemWatcher
{
    [PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
    public static void WatcherStrat(string path)
    {
        var watcher = new FileSystemWatcher { Path = path, Filter = "*.*" };
        watcher.Created += new FileSystemEventHandler(OnProcess);
        watcher.EnableRaisingEvents = true;
        watcher.NotifyFilter = NotifyFilters.Attributes | NotifyFilters.CreationTime | NotifyFilters.DirectoryName | NotifyFilters.FileName | NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.Security | NotifyFilters.Size;
        watcher.IncludeSubdirectories = true;
    }
    public static void OnProcess(object source, FileSystemEventArgs e)
    {
        switch (e.ChangeType)
        {
            case WatcherChangeTypes.Created:
                OnCreated(source, e);
                break;
        }
    }
    public static void OnCreated(object source, FileSystemEventArgs e)
    {
        Console.WriteLine("文件改变事件{0}文件路径{1}文件名{2}", e.ChangeType, e.FullPath, e.Name);
    }
    public static void OnChanged(object source, FileSystemEventArgs e)
    {
        Console.WriteLine("文件改变事件{0}文件路径{1}文件名{2}", e.ChangeType, e.FullPath, e.Name);
    }
    public static void OnDeleted(object source, FileSystemEventArgs e)
    {
        Console.WriteLine("文件删除事件{0}文件路径{1}文件名{2}", e.ChangeType, e.FullPath, e.Name);
    }
    public static void OnRenamed(object source, RenamedEventArgs e)
    {
        Console.WriteLine("文件重命名事件{0}文件路径{1}文件名{2}", e.ChangeType, e.FullPath, e.Name);
    }
    public static void GetFilesSystemRights(string path)
    {
        //给文件添加"Everyone,Users"用户组的完全控制权限  
        var fi = new FileInfo(path);
        System.Security.AccessControl.FileSecurity fileSecurity = fi.GetAccessControl();
        fileSecurity.AddAccessRule(new FileSystemAccessRule("Everyone", FileSystemRights.FullControl, AccessControlType.Allow));
        fileSecurity.AddAccessRule(new FileSystemAccessRule("Users", FileSystemRights.FullControl, AccessControlType.Allow));
        fi.SetAccessControl(fileSecurity);
        //给文件所在目录添加"Everyone,Users"用户组的完全控制权限  
        var di = new DirectoryInfo(path);
        System.Security.AccessControl.DirectorySecurity dirSecurity = di.GetAccessControl();
        dirSecurity.AddAccessRule(new FileSystemAccessRule("Everyone", FileSystemRights.FullControl, AccessControlType.Allow));
        dirSecurity.AddAccessRule(new FileSystemAccessRule("Users", FileSystemRights.FullControl, AccessControlType.Allow));
        di.SetAccessControl(dirSecurity);

    }
}

在Global.asax文件中添加MyFileSystemWatcher.WatcherStrat("文件夹路径");以便在服务启动时就开始监测文件夹。

.BAD文件是邮件的实际内容；

.BDP是无用信息的回集；

.BDR文件显示了邮件没有被发送的原因