To add a new attribute with a single value:
$entry[mail] = "[email protected]";
$results = ldap_mod_add($ldapConnID, $dn, $entry);
To add a new attribute with multiple values:
$entry[mail][] = "[email protected]";
$entry[mail][] = "[email protected]";
$results = ldap_mod_add($ldapConnID, $dn, $entry);