// Create POP3 object
Pop3 pop = new Pop3();

// Enable logging to file
pop.Log.Enabled = true;
pop.Log.Filename = @"C:\log.txt";
pop.Log.Clear();

// Connect to POP3 server
pop.Connect("mail.domain.com");
pop.Login("bounce", "secret");

// Download headers and bodies of all messages.
MailMessageCollection msgs = pop.DownloadMessageHeaders(1, -1, -1);
                        
// Loop through all messages in the mailbox
foreach (MailMessage msg in msgs)
{
        string strLine = msg.BodyPlainText;
        Console.WriteLine("From: " + msg.From.Email);
                                
        // Get failed email address
        string str_invalid_email =  GetInvalidEmailAddressME(msg);

        // If str_invalid_email is non-empty then failed email 
        // address was found
        if (str_invalid_email.Length > 0)
        {
                // Remove failed email from database
                RemoveEmailFromDatabase(str_invalid_email);

                // Display invalid adress
                Console.WriteLine("Invalid email: " + str_invalid_email);                

                // Delete bounced email from server to avoid
                // processing it next time
                pop.DeleteMessage(msg.IndexOnServer);
        }
}

// Disconnect from POP3 server
pop.Disconnect();

// The function checks whether the message is bounced and extracts 
// failed address 
// from bounced message. Valid only for MailEnable servers
static string  GetInvalidEmailAddressME(MailMessage msg)
{
        string str_invalid_email = msg.BodyPlainText;

        // Check if this is a bounced message report
        if (msg.Subject.IndexOf("Delivery Failure") == -1)
{ 
                return "";
        }
        if (msg.From.ToString().IndexOf("POSTMASTER") == -1)
        {
                return "";
        }

        // Now we're sure this is a bounced message report
        int i_start;
        i_start = str_invalid_email.IndexOf("SMTP:");

        // Check if bounced message report contains "Recipient:" field
        if (i_start == -1)
        {
                return "";
        }
                        
        // Get failed address
        i_start += 5;
        i_end = str_invalid_email.IndexOf("]",i_start);
        str_invalid_email.Substring(i_start, i_end);
                        
        return str_invalid_email;
}

// The function checks whether the message is bounced and extracts 
// failed address 
// from bounced message. Valid only for Communigate Pro servers
static string  GetInvalidEmailAddressCP(MailMessage msg)
{
string str_invalid_email = msg.BodyPlainText;

        // Check if this is a bounced message report
        if (msg.Subject.IndexOf("Undeliverable mail") == -1) 
        {
                return "";
        }
        if (msg.From.ToString().IndexOf("MAILER-DAEMON") == -1) 
        {
                return "";
        }

        // Now we're sure this is a bounced message report
        int i_start;
        i_start = str_invalid_email.IndexOf("to '<");

        // Check if bounced message report contains 
        // "Failed to deliver to " field
        if (i_start == -1)
        { 
                return "";
        }
                        
        // Get failed address
        i_start += 5;
        i_end = str_invalid_email.IndexOf("]",i_start);
        str_invalid_email.Substring(i_start, i_end);
                        
        return str_invalid_email;
}

// This function must remove (or disable) specified
// email address from mailing list
static void RemoveEmailFromDatabase(string str_invalid_email)
{
// TODO: Add your code here                        
}

Dim pop As New Pop3

' Enable logging to file
pop.Log.Enabled = True
pop.Log.Filename = "C:\log.txt"
pop.Log.Clear()

' Connect to POP3 server
pop.Connect("mail.domain.com")
pop.Login("jdoe", "secret")

' Download headers and bodies for all messages.
Dim msgs As MailMessageCollection = pop.DownloadMessageHeaders(1, -1, -1)

' Loop through all messages in the mailbox
Dim msg As MailMessage
For Each msg In msgs
        Dim strLine As String = msg.BodyPlainText
        Console.WriteLine("From: " + msg.From.Email)

        ' Get failed email address
        Dim str_invalid_email As String = GetInvalidEmailAddressME(msg)

        ' If str_invalid_email is non-empty then failed email 
        ' address was found
        If str_invalid_email.Length > 0 Then
                'Remove failed email from database
                RemoveEmailFromDatabase(str_invalid_email)

                ' Display invalid address
                Console.WriteLine("Invalid email: " & str_invalid_email)

                ' Delete bounced email from server to avoid
                ' processing it next time
                pop.DeleteMessage(msg.IndexOnServer)
        End If
Next
Console.ReadLine()

' Disconnect from POP3 server
pop.Disconnect()

' The function checks whether the message is bounced and extracts 
' failed address 
' from bounced message. Valid only for MailEnable servers
Function GetInvalidEmailAddressME(ByVal msg As MailMessage) As String
        Dim str_invalid_email As String = msg.BodyPlainText

        ' Check if this is a bounced message report
        If msg.Subject.IndexOf("Delivery Failure") = -1 Then
                Return ""
        End If
        If msg.From.ToString().IndexOf("POSTMASTER") = -1 Then
                Return ""
        End If

        ' Now we're sure this is a bounced message report
        Dim i_start As Integer, i_end As Integer
        i_start = str_invalid_email.IndexOf("SMTP:")

        ' Check if bounced message report contains "Recipient:" field
        If i_start = -1 Then
                Return ""
        End If

        ' Get failed address
        i_start += 5
        i_end = str_invalid_email.IndexOf("]", i_start)
        str_invalid_email.Substring(i_start, i_end)

        Return str_invalid_email
End Function

' The function checks whether the message is bounced and extracts 
' failed address 
' from bounced message. Valid only for Communigate Pro servers
Function GetInvalidEmailAddressCP(ByVal msg As MailMessage) As String
        Dim str_invalid_email As String = msg.BodyPlainText

        ' Check if this is a bounced message report
        If msg.Subject.IndexOf("Undeliverable mail") = -1 Then
                Return ""
        End If
        If msg.From.ToString().IndexOf("MAILER-DAEMON") = -1 Then
                Return ""
        End If

        ' Now we're sure this is a bounced message report
        Dim i_start As Integer, i_end As Integer
        i_start = str_invalid_email.IndexOf("to '<")

        ' Check if bounced message report contains 
        ' "Failed to deliver to " field
        If i_start = -1 Then
                Return ""
        End If

        ' Get failed address
        i_start += 5
        i_end = str_invalid_email.IndexOf("]", i_start)
        str_invalid_email.Substring(i_start, i_end)

        Return str_invalid_email
End Function

' This function must remove (or disable) specified
' email address from mailing list
Sub RemoveEmailFromDatabase(ByVal str_invalid_email As String)
        ' TODO: Add your code here                        
End Sub

• 可靠性。这一方面是代码质量问题，通过为brpc团队设立很高的招聘门槛，以及在团队中深入的技术讨论，我们确保了稳固的代码基础。另一个问题是长尾问题，这是设计问题，brpc其实包含了很多模块，其中的bthread是一个M:N线程库，就是为了更好地提高并发避免阻塞。brpc中的读和写都是wait-free的，这是最高程度的并发。技术细节请点击链接查看。
• 易用性。有种设计是什么选择都做成选项丢给用户，号称功能都有，但一旦出问题，则是用户“配置错了”。而且这样用户还非常依赖开发团队，没有开发团队的支持基本用不了，开发团队有足够的理由扩充团队。这么做其实非常不负责任，用户面对海量的选项也很难受。brpc对于增加选项非常谨慎，框架能自己做判断的绝不扔给用户，所有用户选项都有最合理的默认值，不设也能用。我们认为这对用户体验来说非常重要。
• 定位问题的便利性。这点其它开源框架目前做的都不好，正常使用是可以的，但出问题就麻烦了。这个问题在百度内部其实也很严重，brpc之前用户排查问题都要拉RPC同学一起排查，RPC框架对用户是个黑盒，用户根本不知道里面发生了什么。按我们的经验，基本每天都有几个用户在群里问server卡顿，client超时之类的问题，排查问题是常态，人手必然不够。时间长了用户就觉得你这个框架各种问题，人还拽的不行很少回他们消息。brpc的解决办法是给server内加入各种HTTP接口的内置服务，通过这些服务，用户可以很快看到server的延时、错误、连接、跟踪某个RPC、CPU热点、内存分配、锁竞争等信息，用户还可以使用bvar来自定义各类统计信息，并在百度的运维平台NOAH上汇总。这样大部分问题用户可以自助解决。其实我们去看也是看这些，只是会更加专业。内置服务的具体说明可以看这里。

• 对协议的抽象更一般化，并统一了全百度的通信架构。bprc能容纳非常多的协议，基于Protobuf的，基于HTTP的，百度内的nshead/mcpack，开源的Redis/Memcached，甚至RTMP/FLV/HLS直播协议，brpc能逐渐地嵌入现有系统，而不需要彻底重构，但sofa-pbrpc则不具备扩展协议的能力。类似的，sofa-pbrpc也无法定制负载均衡算法，brpc默认提供round-robin、随机、一致性哈希，Locality-aware（局部性感知）四种算法，用户还能定制。
• 多线程质量更好。多线程编程是非常困难的，看起来简单的RPC遍布多线程陷阱，比如处理超时的代码可能在RPC还没发出去时就运行了；发送函数还没结束，处理回复的回调就被运行了；一个回复还在被处理另一个回复回来了，诸如此类。另外，一个异步RPC的回调里发起一个同步RPC会发生什么，带着锁做同步RPC会发生什么。这些问题我们都不能在sofa-pbrpc中找到满意的答案。
• 完备的调试和运维支持。解决这个问题的本质还在可扩展性，你如何让用户参与进来定制他们感兴趣的指标，为此我们设计了bvar，让用户能用比原子变量代价还小的方式自由地定制各种指标，用户能在浏览器上看到指标的变化曲线，或在运维平台NOAH看到汇总的监控数据。brpc还加入了大量内置服务方便用户调试程序，查看连接，在线修改gflags，追踪RPC，分析CPU热点，内存分配，锁竞争等一应俱全。

• 百度地图API入口
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