用汇编语言写ESMTP邮件发送程序

下载本节例子程序和源代码 (9.67 KB)
最近在CSDN论坛上看到许多人问着同一个问题——如何编写带服务器验证的 ESMTP 邮件发送程序，回答的人还真不少：有建议用 MAPI 的、有建议使用别人的类库的……其实我对此是颇不以为然的。ESMTP 的编写并不困难，关键是弄清楚了协议——只要严格按照协议来进行，就一定能OK，反而编程的技巧在此倒是无足轻重的。换句话说，写这个程序是Easy job，没有必要用到 MAPI 等“庞然大物”啊。

既然如此，让我们来使用 Win32ASM 编写一个自己的 ESMTP “引擎”，可以用在你的病毒或者木马上哦！  ：）

我们先来看看 SMTP 的发送协议，在 rfc821(smtp) 和 rfc1521(mime) 里面写得非常清楚，读者请自行参考这两个文档。什么？看不懂英文？……没关系，我给大家整理一下。ESMTP 的整个发送过程如下：

Socket连接后，按 ESMTP 协议通讯（注意每条命令结尾符“回车/换行/./回车/换行”结束）：
1、EHLO <Domain>/r/n
        这条命令可以不要，但是按照标准的写法，还是加上好。
        Example： EHLO smtp.163.net/r/n
2、AUTH LOGIN/r/n
        告诉服务器，要进行验证了。
3、Base64_Username/r/n
        发送经过 Base64 编码的用户名给服务器。
4、Base64_Password/r/n
        发送经过 Base64 编码的密码给服务器。
5、MAIL FROM:/r/n
        发送者的Email地址。
        Example： MAIL FROM: [e-mail]/r/n
6、RCPT TO:/r/n
        目标Email地址。
        Example： RCPT TO: [e-mail]/r/n
7、DATA/r/n
        开始传送数据。
8、发送数据/r/n./r/n
        注意：SMTP协议只发送信息，至于如何区分CC、BCC、Subject、Body等不属于SMTP的范围，详情请查看RFC文档MAIL格式部分
        简单说一下MAIL格式：Sunject:<主题>/r/n/r/n<内容>，还有好多……
        返回值为“250 ***”表示正常，同时***里含有MessageID等信息（前面的命令都有相应的返回信息）
9、QUIT/r/n
        Over，走人……
上面的是 ESMTP 的协议，如果我们严格按照上面的协议，就可以写出 ESMTP 的发送程序了。大家看出来了吗？其实 ESMTP 与 SMTP 唯一不同的地方，就是在于第三步和第四步——缺少了这两个步骤， ESMTP 就等于 SMTP 了。

至于如何区分正文和附件，其实是在 DATA/r/n 后，通过一个叫做“Boundary”的分隔字符串来分隔开来的，这个“Boundary”可以是任意的字符串，随你喜欢怎么取都行，但是必须注意的是，分隔的时候要按照“--Boundary”的格式，结束的时候要用“--Boundary--”。而附件的内容，是通过 Base64 编码，包含在 DATA 里面进行发送；如果有多个附件，就要进行循环，把每个附件的内容包含进去，直至结束。

这样说会不会太抽象了？好吧，我举个例子：

"EHLO smtp.163.net", 13, 10
"AUTH LOGIN", 13, 10
"lcother", 13, 10
"lcother_password", 13, 10
"MAIL FROM:[e-mail]", 13, 10
"RCPT TO:[e-mail]", 13, 10
"DATA", 13, 10
"From: 老罗", 13, 10,/
"To: Somebody", 13, 10, /
"Subject: 你好吗？", 13, 10, 0
"MIME-Version: 1.0", 13, 10, /
"X-Mailer: LCMailer by LC", 13, 10, /
"Content-type:multipart/mixed;Boundary=www.LuoCong.com", 13, 10, 13, 10, /
"--www.LuoCong.com", 13, 10, /
"Content-type:text/plain;Charset=GB2312", 13, 10, /
"Content-Transfer-Encoding:8bit", 13, 10, 13, 10, /
"好久不见，最近过得好吗？（正文内容）", 13, 10, 13, 10, 0, /
.if (有附件)
    "--www.luocong.com", 13, 10, /
    .while (files to be sent)
        13, 10, /
        13, 10, /
        "--", 13, 10, /
        "Content-Type:application/octet-stream;Name=文件名", 0, /
        "Content-Disposition:attachment;FileName=文件名", 0, /
        13, 10, /
        "Content-Transfer-Encoding:Base64", 13, 10, 13, 10, 0, /
        经过 Base64 编码的文件内容, 13, 10, 0/
    .endw
.endif
13, 10, /
"--www.luocong.com--", /
13, 10, ".", 13, 10
"QUIT", 13, 10
最后我再给出一个用 Win32ASM 写的 ESMTP 发送程序。值得注意的是，为了尽量简化程序，我没有处理服务器返回的消息，而且我在内存的动态分配上偷懒了，附件的发送有可能会出错。如果你有兴趣对它进行研究，请自行想办法解决吧。如果它倒了你的胃口，那……我真的是实在抱歉！  ^_^  （代码写得很糟糕，我没有时间去 debug 了，见谅！！）


--------------- 主程序 ---------------
文件名： smtp.asm
--------------------------------------

;***********************************************
;程序名称：演示ESmtp发送原理
;作者：罗聪
;日期：2002-11-2
;出处：http://www.luocong.com（老罗的缤纷天地）
;注意事项：如欲转载，请保持本程序的完整，并注明：
;转载自“老罗的缤纷天地”（http://www.luocong.com）
;***********************************************

.386
.model flat, stdcall
option casemap:none

include /masm32/include/windows.inc
include /masm32/include/kernel32.inc
include /masm32/include/user32.inc
include /masm32/include/comdlg32.inc
include /masm32/include/wsock32.inc
include /masm32/include/masm32.inc
includelib /masm32/lib/kernel32.lib
includelib /masm32/lib/user32.lib
includelib /masm32/lib/comdlg32.lib
includelib /masm32/lib/wsock32.lib
includelib /masm32/lib/masm32.lib


WndProc              proto    :DWORD, :DWORD, :DWORD, :DWORD
Base64Encode         proto    :DWORD, :DWORD, :DWORD


.const
IDI_LC               equ    1
IDC_BUTTON_SEND      equ    3000
IDC_EDIT_SMTPSERVER  equ    3001
IDC_EDIT_USERNAME    equ    3002
IDC_EDIT_PASSWORD    equ    3003
IDC_EDIT_FROM        equ    3004
IDC_EDIT_TO          equ    3005
IDC_EDIT_SUBJECT     equ    3006
IDC_EDIT_CONTENT     equ    3007
IDC_EDIT_ATTACHMENT  equ    3008
IDC_BUTTON_BROWSE    equ    3009
MAXNUM               equ    2048
MAXFILESIZE          equ    87380


.data
szDlgName            db    "lc_dialog", 0
szCaption            db    "ESmtp demo by LC, 2002-10-12", 0
szErrNoDll           db    "装载winsock.dll时出错！", 0
szErrSocket          db    "建立socket时出错！", 0
szErrConnect         db    "进行连接时出错！", 0
szErrAuth            db    "用户名/密码 验证失败！", 0
szSuccessSend        db    "发送成功！", 0
szHeloFmt            db    "EHLO %s", 13, 10, 0
szAuth               db    "AUTH LOGIN", 13, 10, 0
szUsernameFmt        db    "%s", 13, 10, 0
szPasswordFmt        db    "%s", 13, 10, 0
szHeaderFmt          db    "MAIL FROM:%s", 13, 10
                     db    "RCPT TO:%s", 13, 10, 0
szBody1Fmt           db    "DATA", 13, 10
                     db    "From:%s", 13, 10
                     db    "To:%s", 13, 10
                     db    "Subject:%s", 13, 10
                     db    "MIME_Version:1.0", 13, 10
                     db    "Content-type:multipart/mixed;Boundary=www.LuoCong.com", 13, 10, 13, 10
                     db    "--www.LuoCong.com", 13, 10
                     db    "Content-type:text/plain;Charset=GB2312", 13, 10
                     db    "Content-Transfer-Encoding:8bit", 13, 10, 13, 10
                     db    "%s", 13, 10, 13, 10, 0
szBody2              db    "--www.LuoCong.com", 13, 10, 0
szBody3              db    "Content-Type:application/octet-stream;Name=", 0
szBody4              db    13, 10, 0
szBody5              db    "Content-Disposition:attachment;FileName=", 0
szBody6              db    13, 10, 0
szBody7              db    "Content-Transfer-Encoding:Base64", 13, 10, 13, 10, 0
szBody8              db    13, 10, 13, 10, 0
szBodyEnd            db    "--www.LuoCong.com--"
                     db    13, 10, "." , 13, 10, 0
szQuit               db    "QUIT", 13, 10, 0
dwSize               dd    0
ofn                  OPENFILENAME    <>
szFilterString       db    "所有文件", 0, "*.*", 0, 0
szMyTitle            db    "请打开一个文件作为附件！", 0
reply_val            dd    0
wsadata              WSADATA        <>
sin                  sockaddr_in    <>

;下面是为了方便调试，预设的各项参数：
sz1                  db    "smtp.163.net", 0
sz2                  db    "lcother", 0
sz3                  db    "lcother", 0
sz4                  db    "[e-mail]", 0
sz5                  db    "[e-mail]", 0
sz6                  db    "最近如何？", 0
sz7                  db    "你好吗？", 0

;Base64 -> ASCII mapping table
base64_alphabet      db    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="


.data?
hInstance            dd    ?
hSocket              dd    ?
szSmtpServer         db    255 dup(?)
szFileName           db    256 dup(?)
szBuffer             db    MAXNUM    dup(?)
szBuf1               db    MAXNUM    dup(?)
szBuf2               db    MAXNUM    dup(?)
szBuf3               db    MAXNUM    dup(?)
szHelo               db    MAXNUM    dup(?)
szUsername           db    MAXNUM    dup(?)
szPassword           db    MAXNUM    dup(?)
szHeader             db    MAXNUM    dup(?)
szContent            db    MAXFILESIZE    + 2048 dup(?)


.code
main:
    invoke GetModuleHandle, NULL
    mov hInstance, eax
    invoke DialogBoxParam, hInstance, offset szDlgName, 0, WndProc, 0
    invoke ExitProcess, eax

WndProc proc hWnd:HWND, uMsg:UINT, wParam:WPARAM, lParam:LPARAM
    LOCAL hFile: HANDLE
    LOCAL hMapFile: HANDLE
    LOCAL dwFileSize: DWORD
    LOCAL pMemory: DWORD
    LOCAL pContent: DWORD
    LOCAL pFileContent: DWORD

    .if uMsg == WM_CLOSE
        invoke EndDialog, hWnd, 0

    .elseif    uMsg == WM_INITDIALOG
        invoke LoadIcon, hInstance, IDI_LC
        invoke SendMessage, hWnd, WM_SETICON, ICON_SMALL, eax

        ;下面是为了方便调试，填入预设的各项参数：
        invoke SetDlgItemText, hWnd, IDC_EDIT_SMTPSERVER, addr sz1
        invoke SetDlgItemText, hWnd, IDC_EDIT_USERNAME, addr sz2
        invoke SetDlgItemText, hWnd, IDC_EDIT_PASSWORD, addr sz3
        invoke SetDlgItemText, hWnd, IDC_EDIT_FROM, addr sz4
        invoke SetDlgItemText, hWnd, IDC_EDIT_TO, addr sz5
        invoke SetDlgItemText, hWnd, IDC_EDIT_SUBJECT, addr sz6
        invoke SetDlgItemText, hWnd, IDC_EDIT_CONTENT, addr sz7

    .elseif uMsg == WM_COMMAND
        mov eax, wParam
        mov edx, eax
        shr edx, 16
        movzx eax, ax
        .if edx == BN_CLICKED
            .if eax == IDC_BUTTON_SEND
                ;以下是初始化 winsock ：
                invoke WSAStartup, 101h, addr wsadata
                .if eax != NULL
                    invoke MessageBox, hWnd, addr szErrNoDll, addr szCaption, MB_OK or MB_ICONHAND
                .else
                    invoke socket, AF_INET, SOCK_STREAM, 0
                    .if eax == INVALID_SOCKET
                        invoke MessageBox, hWnd, addr szErrSocket, addr szCaption, MB_OK or MB_ICONHAND
                    .else
                        mov hSocket, eax
                        mov sin.sin_family, AF_INET
                        invoke htons, 25
                        mov sin.sin_port, ax
                        invoke GetDlgItemText, hWnd, IDC_EDIT_SMTPSERVER, addr szSmtpServer, 255
                        invoke gethostbyname, addr szSmtpServer
                        mov eax, [eax + 12]
                        mov eax, [eax]
                        mov eax, [eax]
                        mov sin.sin_addr, eax
                        invoke connect, hSocket, addr sin, sizeof sin
                        .if eax < 0
                            invoke MessageBox, hWnd, addr szErrConnect, addr szCaption, MB_OK or MB_ICONHAND
                        .else
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM
                            invoke RtlZeroMemory, addr szBuf1, MAXNUM
                            invoke RtlZeroMemory, addr szBuf2, MAXNUM
                            invoke RtlZeroMemory, addr szBuf3, MAXNUM
                            ;发送 Helo ：
                            invoke wsprintf, addr szHelo, addr szHeloFmt, addr szSmtpServer
                            invoke lstrlen, addr szHelo
                            invoke send, hSocket, addr szHelo, eax, 0
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM

                            ;发送 Auth ：
                            invoke lstrlen, addr szAuth
                            invoke send, hSocket, addr szAuth, eax, 0

                            ;发送 username:
                            invoke GetDlgItemText, hWnd, IDC_EDIT_USERNAME, addr szBuffer, 100
                            invoke Base64Encode, addr szBuffer, addr szBuf1, eax
                            invoke wsprintf, addr szUsername, addr szUsernameFmt, addr szBuf1
                            invoke lstrlen, addr szUsername
                            invoke send, hSocket, addr szUsername, eax, 0
                            invoke RtlZeroMemory, addr szBuf1, MAXNUM
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM

                            ;发送 password:
                            invoke GetDlgItemText, hWnd, IDC_EDIT_PASSWORD, addr szBuffer, 100
                            invoke Base64Encode, addr szBuffer, addr szBuf1, eax
                            invoke wsprintf, addr szPassword, addr szPasswordFmt, addr szBuf1
                            invoke lstrlen, addr szPassword
                            invoke send, hSocket, addr szPassword, eax, 0
                            invoke RtlZeroMemory, addr szBuf1, MAXNUM
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM

                            ;获得服务器返回的消息：
                            invoke recv, hSocket, addr szBuffer, MAXNUM, 0
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM
                            invoke recv, hSocket, addr szBuffer, MAXNUM, 0
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM
                            invoke recv, hSocket, addr szBuffer, MAXNUM, 0
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM
                            invoke recv, hSocket, addr szBuffer, MAXNUM, 0
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM
                            invoke recv, hSocket, addr szBuffer, MAXNUM, 0

                            ;得到返回消息的前三个数字：
                            mov byte ptr [szBuffer + 3], 0
                            invoke atodw, addr szBuffer
                            mov reply_val, eax
                            invoke RtlZeroMemory, addr szBuffer, MAXNUM

                            ;判断用户名/密码是否正确：
                            .if reply_val != 235
                                invoke MessageBox, hWnd, addr szErrAuth, addr szCaption, MB_OK or MB_ICONHAND
                            .else
                                ;发送 Header ：
                                invoke GetDlgItemText, hWnd, IDC_EDIT_FROM, addr szBuf1, MAXNUM
                                invoke GetDlgItemText, hWnd, IDC_EDIT_TO, addr szBuf2, MAXNUM
                                invoke wsprintf, addr szHeader, addr szHeaderFmt, addr szBuf1, addr szBuf2
                                invoke lstrlen, addr szHeader
                                invoke send, hSocket, addr szHeader, eax, 0

                                ;准备好 Body1 的内容：
                                invoke GetDlgItemText, hWnd, IDC_EDIT_SUBJECT, addr szBuf3, MAXNUM
                                add dwSize, eax
                                invoke GetDlgItemText, hWnd, IDC_EDIT_CONTENT, addr szBuffer, MAXNUM
                                add dwSize, eax
                                ;分配内存：
                                ;（这里为了方便，只分配了 10000000 个字节，
                                ;其实应该根据实际需要进行动态分配，否则有可能会导致错误）
                                invoke LocalAlloc, LPTR, 10000000
                                mov pContent, eax
                                invoke wsprintf, pContent, addr szBody1Fmt, addr szBuf1, addr szBuf2, addr szBuf3, addr szBuffer
                                invoke RtlZeroMemory, addr szBuffer, MAXNUM

                                ;获取文件名：
                                invoke GetDlgItemText, hWnd, IDC_EDIT_ATTACHMENT, addr szBuffer, MAXNUM
                                .if eax != 0
                                    ;打开文件：
                                    invoke CreateFile, addr szFileName, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL
                                    mov hFile, eax

                                    .if hFile != INVALID_HANDLE_VALUE
                                        ;获得文件长度：
                                        invoke GetFileSize, hFile, NULL
                                        mov dwFileSize, eax

                                        ;建立内存映射文件：
                                        invoke CreateFileMapping, hFile, NULL, PAGE_READONLY, 0, 0, NULL
                                        mov hMapFile, eax

                                        ;映射文件进内存：
                                        invoke MapViewOfFile, hMapFile, FILE_MAP_READ, 0, 0, 0
                                        mov pMemory, eax

                                        ;分配内存：
                                        ;（这里为了方便，只分配了 10000000 个字节，
                                        ;其实应该根据实际需要进行动态分配，否则有可能导致错误）
                                        invoke LocalAlloc, LPTR, 10000000
                                        mov pFileContent, eax

                                        ;进行Base64转换：
                                        invoke Base64Encode, pMemory, pFileContent, dwFileSize

                                        ;准备好 Attachment 的内容：
                                        invoke lstrcat, pContent, addr szBody2
                                        invoke lstrcat, pContent, addr szBody3
                                        invoke lstrcat, pContent, addr szFileName
                                        invoke lstrcat, pContent, addr szBody4
                                        invoke lstrcat, pContent, addr szBody5
                                        invoke lstrcat, pContent, addr szFileName
                                        invoke lstrcat, pContent, addr szBody6
                                        invoke lstrcat, pContent, addr szBody7
                                        invoke lstrcat, pContent, pFileContent
                                        invoke lstrcat, pContent, addr szBody8

                                        ;释放内存：
                                        invoke LocalFree, pFileContent

                                        ;解除文件映射：
                                        invoke UnmapViewOfFile, pMemory
                                        ;关闭内存映射文件：
                                        invoke CloseHandle, hMapFile
                                    
                                        ;关闭文件：
                                        invoke CloseHandle, hFile
                                    .endif
                                .endif

                                ;连接 "/r/n./r/n" 到 Content 中：
                                invoke lstrcat, pContent, addr szBodyEnd
                            
                                ;发送 Content ：
                                invoke lstrlen, pContent
                                invoke send, hSocket, pContent, eax, 0

                                invoke LocalFree, pContent

                                ;发送“QUIT”：
                                invoke send, hSocket, addr szQuit, 4, 0
                                invoke MessageBox, hWnd, addr szSuccessSend, addr szCaption, MB_OK or MB_ICONINFORMATION
                            .endif
                        .endif
                        invoke closesocket, hSocket
                    .endif
                    invoke WSACleanup
                .endif

            .elseif eax == IDC_BUTTON_BROWSE
                ;“打开文件”对话框：
                mov ofn.lStructSize, sizeof ofn
                push hWnd
                pop ofn.hwndOwner
                push hWnd
                pop ofn.hInstance
                mov ofn.lpstrFilter, offset szFilterString
                mov ofn.lpstrFile, offset szFileName
                mov ofn.nMaxFile, 256
                mov ofn.Flags, OFN_FILEMUSTEXIST or OFN_PATHMUSTEXIST or OFN_LONGNAMES or OFN_EXPLORER
                mov ofn.lpstrTitle, offset szMyTitle
                invoke GetOpenFileName, addr ofn
                .if eax != 0
                    ;设置 IDC_EDIT_ATTACHMENT 的内容为文件名：
                    invoke SetDlgItemText, hWnd, IDC_EDIT_ATTACHMENT, addr szFileName
                .endif
            .endif
        .endif

    .else
        mov eax, FALSE
        ret
    .endif
    mov eax, TRUE
    ret
WndProc endp

;**********************************************************
;函数功能：进行Base64编码
;入口参数：
;    source            =    传入的字符串
;    sourcelen        =    传入的字符串的长度
;出口参数：
;    destination        =    返回的编码
;**********************************************************
Base64Encode    proc    uses ebx edi esi source:DWORD, destination:DWORD, sourcelen:DWORD

    mov  esi, source
    mov  edi, destination
@@base64loop:
    xor eax, eax
    .if sourcelen == 1
        lodsb                        ;source ptr + 1
        mov ecx, 2                   ;bytes to output = 2
        mov edx, 03D3Dh              ;padding = 2 byte
        dec sourcelen                ;length - 1
    .elseif sourcelen == 2
        lodsw                        ;source ptr + 2
        mov ecx, 3                   ;bytes to output = 3
        mov edx, 03Dh                ;padding = 1 byte
        sub sourcelen, 2             ;length - 2
    .else
        lodsd
        mov ecx, 4                   ;bytes to output = 4
        xor edx, edx                 ;padding = 0 byte
        dec esi                      ;source ptr + 3 (+4-1)
        sub sourcelen, 3             ;length - 3
    .endif

    xchg al,ah                       ;flip eax completely
    rol  eax, 16                     ;can this be done faster
    xchg al,ah

    @@:
    push  eax
    and   eax, 0FC000000h            ;get the last 6 high bits
    rol   eax, 6                     ;rotate them into al
    mov   al,  byte ptr [offset base64_alphabet + eax]        ;get encode character
    stosb                            ;write to destination
    pop   eax
    shl   eax, 6                     ;shift left 6 bits
    dec   ecx
    jnz   @B                         ;loop

    cmp   sourcelen, 0
    jnz   @@base64loop               ;main loop

    mov   eax, edx                   ;add padding and null terminate
    stosd

    ret
Base64Encode    endp

end main
;********************    over    ********************
;by LC

---------- 主程序的资源文件 ----------
文件名： smtp.rc
--------------------------------------

#include "resource.h"

#define IDI_LC               1
#define IDC_BUTTON_SEND      3000
#define IDC_EDIT_SMTPSERVER  3001
#define IDC_EDIT_USERNAME    3002
#define IDC_EDIT_PASSWORD    3003
#define IDC_EDIT_FROM        3004
#define IDC_EDIT_TO          3005
#define IDC_EDIT_SUBJECT     3006
#define IDC_EDIT_CONTENT     3007
#define IDC_EDIT_ATTACHMENT  3008
#define IDC_BUTTON_BROWSE    3009
#define IDC_STATIC           -1

IDI_LC    ICON    "lc.ico"

LC_DIALOG DIALOGEX 10, 10, 200, 280
STYLE DS_SETFONT | DS_CENTER | WS_MINIMIZEBOX | WS_VISIBLE | WS_CAPTION | WS_SYSMENU
CAPTION "ESmtp demo by LC, 2002-11-2"
FONT 9, "宋体", 0, 0, 0x0
BEGIN
    GROUPBOX        "服务器信息", IDC_STATIC, 5, 5, 190, 60
    LTEXT           "SMTP服务器：", IDC_STATIC, 15, 20, 50, 10
    LTEXT           "用  户  名：", IDC_STATIC, 15, 35, 50, 10
    LTEXT           "密      码：", IDC_STATIC, 15, 50, 50, 10
    GROUPBOX        "邮件信息", IDC_STATIC, 5, 75, 190, 170
    LTEXT           "发信人电邮：", IDC_STATIC, 15, 90, 50, 10
    LTEXT           "收信人电邮：", IDC_STATIC, 15, 105, 50, 10
    LTEXT           "主      题：", IDC_STATIC, 15, 120, 50, 10
    LTEXT           "附      件：", IDC_STATIC, 15, 135, 50, 10
    EDITTEXT        IDC_EDIT_SMTPSERVER, 65, 20, 120, 10, ES_AUTOHSCROLL | NOT WS_BORDER, WS_EX_STATICEDGE
    EDITTEXT        IDC_EDIT_USERNAME, 65, 35, 120, 10, ES_AUTOHSCROLL | NOT WS_BORDER, WS_EX_STATICEDGE
    EDITTEXT        IDC_EDIT_PASSWORD, 65, 50, 120, 10, ES_PASSWORD | ES_AUTOHSCROLL | NOT WS_BORDER, WS_EX_STATICEDGE
    EDITTEXT        IDC_EDIT_FROM, 65, 90, 120, 10, ES_AUTOHSCROLL | NOT WS_BORDER, WS_EX_STATICEDGE
    EDITTEXT        IDC_EDIT_TO, 65, 105, 120, 10, ES_AUTOHSCROLL | NOT WS_BORDER, WS_EX_STATICEDGE
    EDITTEXT        IDC_EDIT_SUBJECT, 65, 120, 120, 10, ES_AUTOHSCROLL | NOT WS_BORDER, WS_EX_STATICEDGE
    EDITTEXT        IDC_EDIT_ATTACHMENT, 65, 135, 100, 10, ES_AUTOHSCROLL | NOT WS_BORDER | ES_READONLY | NOT WS_TABSTOP, WS_EX_STATICEDGE
    PUSHBUTTON      "..", IDC_BUTTON_BROWSE, 170, 135, 15, 10, BS_FLAT | BS_RIGHT | BS_BOTTOM
    EDITTEXT        IDC_EDIT_CONTENT, 15, 150, 170, 85, ES_AUTOVSCROLL | NOT WS_BORDER | WS_VSCROLL | ES_WANTRETURN | ES_MULTILINE, WS_EX_STATICEDGE
    DEFPUSHBUTTON   "发送(&G)", IDC_BUTTON_SEND, 70, 255, 50, 15, BS_FLAT
END

我相信我已经把 ESMTP 的协议说明白了。如果你还有不太明白的地方，欢迎给我来信。[e-mail]

老罗
2002-11-2