C # send mail content and attachments based on SMTP protocol and socket communication, and hide recipients

After several days of hard work, from completely understanding SMTP to tossing out a demo that can send mail content and attachments. To put it bluntly, go directly to the code.

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Net.Sockets;using System.IO;namespace UtilSp.ClassLib{    public class SmtpSp    {        #region Member        #region boundary normal Property        private string boundary_ = Guid.NewGuid().ToString();//Generate unique boundary.        public string boundary_pro        {            get            {                return boundary_;            }            set            {                boundary_ = value;            }        }        #endregion        #region exception  Property        private Exception exception_ = null;        public Exception exception_pro        {            get            {                return exception_;            }            set            {                exception_ = value;            }        }        #endregion        #region encoding_smtp normal Property        private Encoding encoding_smtp_ = Encoding.ASCII;//smtp encoding must be ascii.        private Encoding encoding_smtp_pro        {            get            {                return encoding_smtp_;            }        }        #endregion        #region encoding_subject normal Property        private Encoding encoding_subject_ = Encoding.UTF8;        public Encoding encoding_subject_pro        {            get            {                return encoding_subject_;            }            set            {                encoding_subject_ = value;            }        }        #endregion        #region encoding_content normal Property        private Encoding encoding_content_ = Encoding.GetEncoding("gb2312");        public Encoding encoding_content_pro        {            get            {                return encoding_content_;            }            set            {                encoding_content_ = value;            }        }        #endregion        #region receiveInfo normal Property        private string receiveInfo_ = "";        public string receiveInfo_pro        {            get            {                return receiveInfo_;            }            set            {                receiveInfo_ = value;            }        }        #endregion        #region socket normal Property        private Socket socket_;        public Socket socket_pro        {            get            {                return socket_;            }            private set            {                socket_ = value;            }        }        #endregion        #endregion        private sealed class SMTP_BACKS        {            public const string SERVER_READY_OK = "220";            public const string OPERATE_COMPLETE = "250";            public const string AUTH_LOGIN_OK = "334";            public const string USER_NAME_LOGIN_OK = "334";            public const string PASSWORD_LOGIN_OK = "235";            public const string DATA_OK = "354";        }        private sealed class SMTP_CMD        {            public const string AUTH_LOGIN = "auth login\r\n";            public const string MAIL_FROM = "mail from:";            public const string RCPT_TO = "rcpt to:";            public const string SEND_BODY = "data\r\n";            public const string VERIFY = "ehlo hello\r\n";        }        public sealed class MailInfo        {            #region attachments normal Property            private List<string> attachments_ = new List<string>();            public List<string> attachments_pro            {                get                {                    return attachments_;                }                set                {                    attachments_ = value;                }            }            #endregion            #region content normal Property            private string content_ = "";            public string content_pro            {                get                {                    return content_;                }                set                {                    content_ = value;                }            }            #endregion            #region password normal Property            private string password_ = "";            public string password_pro            {                get                {                    return password_;                }                set                {                    password_ = value;                }            }            #endregion            #region receiverAddresses normal Property            private List<string> receiverAddresses_ = new List<string>();            public List<string> receiverAddresses_pro            {                get                {                    return receiverAddresses_;                }                set                {                    receiverAddresses_ = value;                }            }            #endregion            #region senderAddress normal Property            private string senderAddress_ = "";            public string senderAddress_pro            {                get                {                    return senderAddress_;                }                set                {                    senderAddress_ = value;                }            }            #endregion            #region subject normal Property            private string subject_ = "";            public string subject_pro            {                get                {                    return subject_;                }                set                {                    subject_ = value;                }            }            #endregion            #region userName normal Property            private string userName_ = "";            public string userName_pro            {                get                {                    return userName_;                }                set                {                    userName_ = value;                }            }            #endregion        }        #region send Function        public bool send(string mailHostIP, int port, MailInfo mailInfo)        {            try            {                exception_pro = null;                if (!isLegal(mailHostIP, port, mailInfo))                {                    return false;                }                socket_pro = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);                socket_pro.Connect(mailHostIP, port);                if (!socket_pro.Connected)                {                    socket_pro.Close();                    exception_pro = new Exception(Tip.ConnectFail);                    return false;                }                if (!isServerReady())                {                    exception_pro = new Exception(Tip.ServerReadyFail + analyReceiveError());                    socket_pro.Close();                    return false;                }                if (!verify())                {                    exception_pro = new Exception(Tip.VerifyFail + analyReceiveError());                    socket_pro.Close();                    return false;                }                if (!authLogin())                {                    exception_pro = new Exception(Tip.AuthLoginFail + analyReceiveError());                    socket_pro.Close();                    return false;                }                if (!userNameLogin(mailInfo.userName_pro))                {                    exception_pro = new Exception(Tip.UserNameLoginFail + analyReceiveError());                    socket_pro.Close();                    return false;                }                if (!passowrdLogin(mailInfo.password_pro))                {                    exception_pro = new Exception(Tip.PasswordLoginFail + analyReceiveError());                    socket_pro.Close();                    return false;                }                if (!mailFrom(mailInfo.senderAddress_pro))                {                    exception_pro = new Exception(Tip.MailFromFail + analyReceiveError());                    socket_pro.Close();                    return false;                }                if (!rcptTo(mailInfo.receiverAddresses_pro))                {                    exception_pro = new Exception(Tip.RcptToFail + analyReceiveError());                    socket_pro.Close();                    return false;                }                if (!sendMail(mailInfo))                {                    exception_pro = new Exception(Tip.SendMailFail + analyReceiveError());                    socket_pro.Close();                    return false;                }                socket_pro.Close();                return true;            }            catch (System.Exception ex)            {                exception_pro = ex;                return false;            }        }        private string analyReceiveError()        {            if (string.IsNullOrEmpty(receiveInfo_pro))            {                return Tip.ReceiveInfoEmpty;            }            return receiveInfo_pro;        }        #endregion        private int socketSend(string sendStr)        {            byte[] sendBuffer = encoding_smtp_pro.GetBytes(sendStr);            return socket_pro.Send(sendBuffer);        }        private string receive()        {            byte[] receiveData = new byte[10240];            int receiveLen = socket_pro.Receive(receiveData);            receiveInfo_pro = encoding_smtp_pro.GetString(receiveData, 0, receiveLen);            Console.WriteLine(receiveInfo_pro);            return receiveInfo_pro;        }        #region send ready functions        #region isLegal Function        public bool isLegal(string mailHostIP, int port, MailInfo mailInfo)        {            if (!IpPortSp.isPort(port.ToString()))            {                exception_pro = new Exception(Tip.PortIllegal);                return false;            }            if (!MailSp.isMail(mailInfo.senderAddress_pro))            {                exception_pro = new Exception(Tip.SenderIllegal);                return false;            }            return true;        }        #endregion        #region isServerReady Function        public bool isServerReady()        {            string back = receive();            return back.Substring(0, 3).Equals(SMTP_BACKS.SERVER_READY_OK);//Response code from server always is 3 byte length.        }        #endregion        #region verify Function        public bool verify()        {            socketSend(SMTP_CMD.VERIFY);            string[] verifyBacks = receive().Split(new string[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries);            for (int index = 0; index < verifyBacks.Length; index++)            {                string verifyBack = verifyBacks[index];                if (verifyBack.Length <= 3)                {                    return false;                }                if (!verifyBack.Substring(0, 3).Equals(SMTP_BACKS.OPERATE_COMPLETE))                {                    return false;                }            }            return true;        }        #endregion        #region authLogin function        private bool authLogin()        {            socketSend(SMTP_CMD.AUTH_LOGIN);            string authLoginBack = receive();            if (string.IsNullOrEmpty(authLoginBack) || authLoginBack.Length <= 3)            {                return false;            }            return authLoginBack.Substring(0, 3).Equals(SMTP_BACKS.AUTH_LOGIN_OK);        }        #endregion        #region userNameLogin function        private bool userNameLogin(string userName)        {            if (string.IsNullOrEmpty(userName))            {                return false;            }            string base64UserName = Base64Sp.tobase64Str(userName);            socketSend(base64UserName + "\r\n");            string userNameLoginBack = receive();            if (string.IsNullOrEmpty(userNameLoginBack) || userNameLoginBack.Length <= 3)            {                return false;            }            return userNameLoginBack.Substring(0, 3).Equals(SMTP_BACKS.USER_NAME_LOGIN_OK);        }        #endregion        #region passowrdLogin function        private bool passowrdLogin(string password)        {            if (string.IsNullOrEmpty(password))            {                return false;            }            socketSend(Base64Sp.tobase64Str(password) + "\r\n");            string passowrdLoginBack = receive();            if (string.IsNullOrEmpty(passowrdLoginBack) || passowrdLoginBack.Length <= 3)            {                return false;            }            return passowrdLoginBack.Substring(0, 3).Equals(SMTP_BACKS.PASSWORD_LOGIN_OK);        }        #endregion        #region mailFrom function        private bool mailFrom(string senderAddress)        {            socketSend(SMTP_CMD.MAIL_FROM + "<" + senderAddress + ">\r\n");            string mailFromBack = receive();            if (string.IsNullOrEmpty(mailFromBack) || mailFromBack.Length <= 3)            {                return false;            }            return mailFromBack.Substring(0, 3).Equals(SMTP_BACKS.OPERATE_COMPLETE);        }        #endregion        #region rcptTo function        private bool rcptTo(List<string> receiverAddresses)        {            foreach (string receiverAddress in receiverAddresses)            {                socketSend(SMTP_CMD.RCPT_TO + "<" + receiverAddress + ">\r\n");                string rcptBack = receive();                if (string.IsNullOrEmpty(rcptBack) || rcptBack.Length <= 3)                {                    return false;                }                if (!rcptBack.Substring(0, 3).Equals(SMTP_BACKS.OPERATE_COMPLETE))                {                    return false;                }            }            return true;        }        #endregion        #endregion        #region send mail body functions        private bool sendMail(MailInfo mailInfo)        {            socketSend(SMTP_CMD.SEND_BODY);            string back = receive();            if (string.IsNullOrEmpty(back) || back.Length <= 3)            {                return false;            }            if (!back.Substring(0, 3).Equals(SMTP_BACKS.DATA_OK))            {                return false;            }            sendMailHeader(mailInfo);            sendMailContent(mailInfo.content_pro);            sendMailAttachment(mailInfo.attachments_pro);            sendMailTail();            back = receive();            if (string.IsNullOrEmpty(back) || back.Length <= 3)            {                return false;            }            if (!back.Substring(0, 3).Equals(SMTP_BACKS.OPERATE_COMPLETE))            {                return false;            }            return true;        }        private void sendMailAttachment(List<string> attachments)        {            foreach (string attachment in attachments)//Add header per attachment.            {                if (!File.Exists(attachment))                {                    continue;                }                sendAttachmentHeader(attachment);                sendAttachmentData(attachment);            }        }        private void sendAttachmentData(string attachment)        {            byte[] attachmentData = FileSp.readFileBytes(attachment);            socketSend(Convert.ToBase64String(attachmentData));            socketSend("\r\n\r\n");        }        private void sendAttachmentHeader(string attachment)        {            string contentType = "application/octet-stream";//Easy to transmission more format file;            string header = "--" + boundary_pro + "\r\n"                    + "Content-Type:"+contentType+";name=" + attachment + "\r\n"                    + "Content-Transfer-Encoding:base64\r\n"                    + "Content-Disposition:attachment;filename=\"" + attachment + "\"\r\n";            socketSend(header + "\r\n");        }        private void sendMailTail()        {            socketSend("\r\n.\r\n");//. is content end flag.                }        private void sendMailHeader(MailInfo mailInfo)        {            string to = "";            foreach (string receiverAddress in mailInfo.receiverAddresses_pro)            {                to += "To:" + receiverAddress + "\r\n";            }            //if you want to hide receiver,may assign to="To:abc@a.com\r\n";            //string to = "To:abc@a.com\r\n";            socketSend(to);            string from = "From:" + mailInfo.senderAddress_pro + "\r\n";            socketSend(from);           //Avoid subject messy code,adopt encoding header statement.            string subject = "Subject:=?" + encoding_subject_pro.BodyName + "?B?"                            + Base64Sp.tobase64Str(mailInfo.subject_pro, Encoding.UTF8) + "?=\r\n";            socketSend(subject);            string header = "Mime-Version:1.0\r\n"                      + "Content-type:multipart/mixed;"                      + "boundary=\"" + boundary_pro + "\";\r\n"//define content type and boundary value.                      + "Content-Transfer-Encoding:7bit\r\n"                      + "This is a multi-part message in MIME format\r\n";            socketSend(header + "\r\n");        }        private void sendMailContent(string content)        {            sendContentHeader();            sendContentBody(content);        }        private void sendContentBody(string content)        {            //If content is too long,need split some blocks and send.            //Length of one line is always 80 byte.            string newContent = Base64Sp.tobase64Str(content, encoding_content_pro);            socketSend(newContent + "\r\n");        }        private void sendContentHeader()        {            string header = "--" + boundary_pro + "\r\n"//boundary must begin --                 + "Content-type:text/plain;charset=" + encoding_content_pro.BodyName + "\r\n"//Avoid messy code,add charset statement.                 + "Content-Transfer-Encoding:base64\r\n"//Avoid messy code,use encoding base64.            socketSend(header + "\r\n");        }        #endregion        private class Tip//Easy to change other language tip.        {            public static string AuthLoginFail = "Auth login fail!";            public static string ConnectFail = "Connect mail host fail!";            public static string IpIllegal = "Ip is illegal!";            public static string MailFromFail = "Input sender address fail!";            public static string PasswordLoginFail = "Password login fail!";            public static string PortIllegal = "Port is illegal!";            public static string ReceiveInfoEmpty = "Receive info is empty!";            public static string RcptToFail = "Input receiver address fail!";            public static string SenderIllegal = "Sender mail address is illegal!";            public static string SendMailFail = "Send mail fail!";            public static string ServerReadyFail = "Server ready fail!";            public static string UserNameLoginFail = "User name login fail!";            public static string VerifyFail = "Verify identity fail!";        }    }}

For more information, see http://download.csdn.net/detail/xxdddail/5802901.