我自己借用精华区里的MIME类写了一个基本的发信小东东：
default.htm
<html>
<head>
<script language=javascript>
<!--
function cookieset(){
d=new Date()
d.setFullYear(2001,0,1)
document.cookie="sendmailbox="+document.sendmailform.sendmailbox.value + ";expires=" + d.toGMTString()
alert("设置成功！")
}
function setupdatevalue(){
document.sendmailform.update.value=document.sendmailform.myfile.value
if(document.sendmailform.receivemailbox.value==""){
alert("错误!请填写收信人地址!")
document.sendmailform.receivemailbox.focus()
return(false)
}
}
function readcookie(){
cookievalue=document.cookie
pairs=cookievalue.split(";")
for(i=0;i<pairs.length;i++){
pairsplit=pairs[i].split("=")
if(pairsplit[0]=="sendmailbox") break
}
return(pairsplit[1])
}
//-->
</script>
<title>我的PHP发信箱</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<style type="text/css">
<!--
.smallfont { font-family: "宋体"; font-size: 9pt}
-->
</style>
</head>
<body bgcolor="#FFFFFF" onload=document.sendmailform.receivemailbox.focus()>
<p align="center">欢迎使用我的发信页面</p>
<form method="post" action="sendmail.php4" name=sendmailform enctype="multipart/form-data" onsubmit="return setupdatevalue()">
<table width="55%" border="0" cellspacing="0" cellpadding="2" align="center" class="smallfont">
<tr>
<td width="33%">收信人信箱：</td>
<td width="67%">
<input type="text" name="receivemailbox" size="30" maxlength="40">
</td>
</tr>
<tr>
<td width="33%">发信人信箱：</td>
<td width="67%">
<script language=javascript>
document.write ("<input type='text' name='sendmailbox' size='30' maxlength='40' value='" + readcookie() + "'>")
</script>
<input type="button" name="setcookie" value="设为默认发信信箱" onclick=cookieset()>
</td>
</tr>
<tr>
<td width="33%">主 题：</td>
<td width="67%">
<input type="text" name="subject" maxlength="250" size="40">
</td>
</tr>
<tr>
<td width="33%">附 件：</td>
<td width="67%">
<input type="file" name="myfile">
<input type="hidden" name=update>
</td>
</tr>
<tr>
<td width="33%" valign="top">正 文：</td>
<td width="67%">
<textarea name="bodytext" cols="40" rows="8"></textarea>
</td>
</tr>
<tr>
<td colspan="2" valign="top">
<div align="center">
<input type="submit" name="Submit" value="发送信件">
<input type="reset" name="reset" value="重新填写">
</div>
</td>
</tr>
</table>