You need:
$result = mysql_query("INSERT INTO MESSAGES (RECIPIENT, FROM, DATE, SUBJECT, MESSAGE, STATUS, TYPE)
VALUES ($_POST[RECIPIENT], $_POST[FROM], $cur_date, $_POST[SUBJECT], $_POST[MESSAGE], 1, 2)") or die(mysql_error());
Although normally you would do something like:
$query = "INSERT INTO MESSAGES (RECIPIENT, FROM, DATE, SUBJECT, MESSAGE, STATUS, TYPE)
VALUES ($_POST[RECIPIENT], $_POST[FROM], $cur_date, $_POST[SUBJECT], $_POST[MESSAGE], 1, 2)";
$result = mysql_query($query) OR die(mysql_error());
Don't forget to sanitise your $_POST inputs otherwise you'll be open to hackers.
Also, database text variables needs quotes around them when inserting e.g.
$POST[SUBJECT] should be '$POST[SUBJECT]'