C and C # can be used to receive emails in a simple manner,

C and C # can be used to receive emails in a simple manner,

The main content of this article is to receive simple emails in two ways, one is through the C language, the other is through the C,

The two methods have many differences in implementation, but they are essentially the same.

I. C language implementation

Steps for receiving emails in C language:

1. Create a TCP connection port: 110 by default

2. Connection to Pop3 server name: for example, "pop3.163.com"

3. authenticated login user account and password

4. send the request and receive the server information. send (...) and return "+ OK"

A. Get the number of emails in the mailbox "STAT \ r \ n" back "+ OK 10 ..."

B. Get the size of each email "LIST \ r \ n"

C. Obtain the first n rows of data of a specified email. "TOP [nMsg] [nLine]"

NMsg: nMsg

NLine: The first nLine line.

D. Get the specified email message content "RETR [nMsg] \ r \ n"

The implementation code is as follows:

 

// Create a TCP connection

1 if ((connection = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == INVALID_SOCKET)2 {3    return INVALID_SOCKET;4 }

 

// Connect to the Pop3 server

1 void ConnectToServer () 2 {3 // set the SockAddr_In address structure 4 SOCKADDR_IN serAddr; 5 serAddr. sin_family = AF_INET; 6 serAddr. sin_port = htons (POP3_PORT);/* POP3_PORT = 110 */
7 // serverName = "POP3.163.com ";
8 serAddr. Records = inet_addr (serverName); 9 if (serAddr. Records = INADDR_NONE) 10 {11 LPHOSTENT lphost; 12 lphost = gethostbyname (serverName); 13 if (lphost! = NULL) 14 {15 serAddr. sin_addr.s_addr = (LPIN_ADDR) lphost-> h_addr)-> S_un.S_addr; 16} 17 else18 {19 WSASetLastError (WSAEINVAL); 20 return; 21} 22 // connect 23 connect (connection, (SOCKADDR *) & serAddr, sizeof (serAddr) 24 return; 25 26}

 

// Receive data

// Obtain the number of emails in the mailbox

1 // get the number of emails 2 int GetNumEmail (SOCKET connection) 3 {4 char sStat [10] = {"STAT \ r \ n "}; 5 char response_buf [RESPONSE_BUFFER_SIZE] = {0}; 6 7 send (connection, sStat, strlen (sStat), 0); 8 if (recv (connection, response_buf, RESPONSE_BUFFER_SIZE, 0) = SOCKET_ERROR) 9 return-1; 10 11 char szResponse [20] = {0}; 12 strncpy (szResponse, response_buf, 3); 13 if (strcmp (szResponse, "+ OK") = 0) // return the correct message content "+ OK 10... "14 return GetNumFromBuf (response_buf); 15 return 0; 16}

 

// Obtain the size of each email

1 // get the size of each Mail 2 BOOL GetList (SOCKET connection) 3 {4 char szList [100] = {0}; 5 sprintf (szList, "LIST \ r \ n"); 6 7 char response_buf [RESPONSE_BUFFER_SIZE] = {0}; 8 send (connection, szList, strlen (szList), 0 ); 9 if (recv (connection, response_buf, RESPONSE_BUFFER_SIZE, 0) = SOCKET_ERROR) 10 return FALSE; 11 12 printf ("receive data: % s", response_buf ); // return data 13 return TRUE; 14}

 

// Obtain the first n rows of data of the specified email

1 // obtain the first n rows of data of the specified email. 2 BOOL GetTop (SOCKET connection, int nMsg, int nLine) 3 {4 char szTop [100] = {0 }; 5 sprintf (szTop, "TOP % d \ r \ n", nMsg, nLine); 6 7 char response_buf [RESPONSE_BUFFER_SIZE] = {0}; 8 send (connection, szTop, strlen (szTop), 0); 9 Sleep (nLine * 20); // latency, waiting for the data to be fully received 10 if (recv (connection, response_buf, RESPONSE_BUFFER_SIZE, 0) = SOCKET_ERROR) 11 return FALSE; 12 13 printf ("Receive Data: % s \ n", response_buf); 14 return TRUE; 15}

// Obtain the content of the specified email

1 // get the content of the specified email 2 BOOL GetEmail (SOCKET connection, int nMsg, char * msg) 3 {4 char sRetr [100] = {0}; 5 sprintf (sRetr, "RETR % d \ r \ n", nMsg); 6 7 char response_buf [RESPONSE_BUFFER_SIZE * 10] = {0}; 8 send (connection, sRetr, strlen (sRetr ), 0); 9 Sleep (1000); // a latency must be added so that data can be fully received 10 if (recv (connection, response_buf, RESPONSE_BUFFER_SIZE * 10, 0) = SOCKET_ERROR) 11 return FALSE; 12 13 printf ("Receive Data: % s \ n", response_buf); 14 return TRUE; 15}

 

I. C # Implementation Method

C # steps for receiving emails:

1. Need to introduce third-party library (OpenPop. dll Official Website: http://sourceforge.net/projects/hpop/), and add OpenPop reference in the project.

2. Use the Pop3Client class in the OpenPop. dll class library to create a Pop3 server object,

Connect to the server and log on to. host: pop3.163.com port: 110 by default

3. Use the method in the Pop3Client object to receive mail information.

A. GetMessageCount () // get the number of emails

B. GetMessage (int messageNumber) // obtain the content of an email numbered messageNumber.

C. GetMessageSize (int messageNumber) // obtain the size of a message numbered messageNumber.

D. DeleteMessage (int messageNumber) // delete an email numbered messageNumber (only marked and deleted after QUIT)

//...

4. Close the connection and release resources.

 

Some code is as follows:

// Create a PopClient object for connection Authentication

1 using (Pop3Client client = new Pop3Client () 2 {3 Client. connect (host, Pop3_Port, false); 4 5 // account, password, authentication method 6 Client. authenticate (userAddr, password, AuthenticationMethod. auto); // login authentication 7 //... 8}

// Obtain the email information in the mailbox

1 //... 2 int count = client. getMessageCount (); // get the total number of mailboxes 3 int size = client. getMessageSize (1); // get the size of the email numbered 1 4 OpenPop. mime. message msg = client. getMessage (1); // obtain the content of the email with the ID of 1 5 client. deleteMessage (1); // The email marked as 1 is "deleted" 6 7 //...

// Obtain the mail header and Attachment Information

1 //... 2 OpenPop. mime. message msg = client. getMessage (1); 3 4 // obtain information from the Headers member in msg 5 string from = msg. headers. from. address; 6 string SendDate = msg. headers. dateSent. toLocalTime (). toString (); 7 string Subject = msg. headers. subject; 8 string Body = msg. findFirstPlainTextVersion (). getBodyText (); 9 10 // get attachment information 11 List <MessagePart> attachments = msg. findAllAttachments (); 12 int attachCount = attachments. count; 13 if (attachCount> 0) 14 {15 string fileName = attachments [0]. fileName; // attachment name 16 17 // Save the attachment content 18 using (FileStream fs = new FileStream (@ "C: \ 01.txt", FileMode. openOrCreate) 19 {20 attachments [0]. save (fs); 21} 22} 23 //...

 

Reference page:

Http://www.yuanjiaocheng.net/CSharp/Csharp-if-else.html

Http://www.yuanjiaocheng.net/CSharp/Csharp-ternary-operator.html

Http://www.yuanjiaocheng.net/CSharp/Cshartp-switch.html

Http://www.yuanjiaocheng.net/CSharp/Csharp-for-loop.html

Http://www.yuanjiaocheng.net/CSharp/Csharp-while-loop.html

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