mail.php: 
 
<?PHP 
 
INCLUDE("dbconn.php"); 
$result1=mysql_query("select * from users WHERE username='$username'") or DIE ("cant do it"); 
$row100 = mysql_fetch_array($result1); 
?> 
| <a href="mail.php?action=compose">Compose</a> | <a href="mail.php?action=inbox">Inbox</a> | 
<table cellpadding="1" cellspacing="1" height="300" width="450"> 
<tr><td align=center valign=top> 
<?PHP 
IF($action==compose) { 
ECHO "<form action=mail.php?action=compose2 method=post>"; 
ECHO "<table>"; 
ECHO "<tr><td>Subject:</td><td><input type=text name=subject size=20 value=$subject></td></tr>"; 
ECHO "<tr><td>To:</td><td><input type=text name=to size=20 value=$to></td></tr>"; 
ECHO "<tr><td>Message:</td><td><textarea rows=16 cols=45 name=message></text></td></tr>"; 
ECHO "<tr><td><button type=submit>Send Mail!</button></td></tr>"; 
ECHO "</table>"; 
ECHO "</form>"; 
} 
IF($action==compose2) { 
$subject or DIE("Subject Blank"); 
$message or DIE("Message Black"); 
$to or DIE("To blank"); 
$date = DATE(YmdHis); 
 
 
$create = "INSERT INTO mail (UserTo, UserFrom, Subject, Message, SentDate, status) 
VALUES ('$to','$username','$subject','$message','$date','unread')"; 
$create2 = mysql_query($create) or DIE("A letter could not be sent to $to!"); 
ECHO("Message Sent to $to!"); 
 
} 
IF($action==inbox) { 
$result=mysql_query("select * from mail where UserTo='$username' ORDER BY SentDate DESC") or DIE ("cant do it"); 
ECHO "<table cellpadding=2 cellspacing=1 width=500 valign=top>"; 
WHILE ($row=mysql_fetch_array($result)) { 
ECHO "<tr><td width=30>Mail:</td><td><a href=mail.php?action=veiw&mail_id=$row[mail_id]>$row[Subject]</a></td><td width=50> <a href=mail.php?action=delete&id=$row[mail_id]><center>Delete</a><br></td></tr>"; 
} 
ECHO "</table>"; 
} 
IF($action==veiw) { 
$result=mysql_query("select * from mail where UserTo='$username' and mail_id=$mail_id") or DIE ("cant do it"); 
$row=mysql_fetch_array($result); 
IF($row[UserTo]==$username) { 
} ELSE { 
ECHO "<font face=verdana><b>This isn't your mail!"; 
EXIT; 
} 
$query="UPDATE mail SET status='read' WHERE UserTo='$username' AND mail_id='$row[mail_id]'"; 
$query or DIE("An error occurred resulting that this message has not been marked read."); 
ECHO "<table border = 1 bordercolor = black width = 50% align=center><tr><td>$row[Subject]</td><td>$row[UserFrom]</td></tr><tr><td colspan='2'>$row[Message]<br><a href=mail.php?action=compose&to=$row[UserFrom]&subject=RE:$row[Subject]>Reply</a></td></tr></table>"; 
$rs = mysql_query("UPDATE mail SET status='read' WHERE mail_id='$mail_id'"); 
} 
IF($action==delete) { 
$query = mysql_query("DELETE FROM mail WHERE mail_id='$id' LIMIT 1"); 
IF($query) { 
ECHO "<font face=verdana>Message Deleted.</font>"; 
} ELSE { 
ECHO "The message wasnt deleted."; 
} 
} 
?> 
 
dbconn.php: 
<?PHP 
 
    $vusername = "username";              //your username for you local system 
    $pwd ="password";                  //password to accecss mySQL 
    $host = "localhost";               //host is localhost - even for most web hosts 
    $dbname = "database";               //db name to be accessed 
 
 
 
    //connect to db 
    //$conn=mysql_connect($host, $username, $pwd) or die ("Unable to connect to database"); 
 
    IF (!($conn=mysql_connect($host, $vusername, $pwd)))  { 
        PRINTF("We couldn't connect to the database right now!"); 
        EXIT; 
    } 
       $db=mysql_select_db($dbname,$conn) or DIE("Unable to connect to database!"); 
 
?> 
 
 
tables: 
CREATE TABLE mail ( 
  UserTo tinytext NOT NULL, 
  UserFrom tinytext NOT NULL, 
  Subject mediumtext NOT NULL, 
  Message longtext NOT NULL, 
  status text NOT NULL, 
  SentDate text NOT NULL, 
  mail_id int(80) NOT NULL auto_increment, 
  PRIMARY KEY  (mail_id) 
) TYPE=MyISAM; 
 
Its easy to embed into your already made member site!