Hm.. Why not write it yourself? Is not too difficult (I know, easy for someone doing this for years).
What you would need:
- A database with the users (name / email / ID / pivate)
a form.
The form contains e.g. a dropdownlist with all the users in it:
$sql = "select Id, email, name from YOURTABLE";
$result = mysdql_query($sql);
while ( $row = mysql_fetch_array($result))
{
$optionlist .= "<option value=\"$id\">$name</option>";
}
When the user submits that form, you just retrieve the email addres fro the database:
$sql = "select email, name from YOURTABLE where id='$_GET[id]'";
$result = mysdql_query($sql);
while ( $row = mysql_fetch_array($result)) // mail the message
{
mail($email, , ); // DO not know the arguments, check the manual at php.net/mail
}