well... that's pretty simple, now that i understand it
the following code is AFTER you submit the form with the url, i'm not going to do any stripping of the url or anthing for http:// or www., etc... since this is a mere example, but you'll want to do that with regex
this is untested for parse errors and actual functionality... you'll have to do that part on your own, but this is a general concept
<?
if ($_POST['submitbutton'] == "Submit Email")
{
$conn = mysql_connect("host", "user", "pass");
$db = mysql_select_db("database");
$url = $_POST['urltext']; //sanitize your code rather than just setting variable
$query = "select url from tablename where url_field = '" . $url . "';"; //this may have to be a LIKE clause depending on how you want to match
$result = mysql_query($query) or die(mysql_error());
if (mysql_num_rows($result) != 0) //this area may need to change also since a LIKE clause could produce more than 1 result, forcing a while loop thru the result set
{
$row = mysql_fetch_array($result);
$email_address = $row['email_address_field'];
//do your mail sending
}
else
{
//handle however you like if there are no such urls in the db
}
}
?>