+ my ($x2, $x38) = ($mid =~ /\A([a-f0-9]{2})([a-f0-9]{38})\z/);
+
+ unless (defined $x38) {
+ # compatibility with old links (or short Message-IDs :)
+ $mid = mid_clean($mid);
+ utf8::encode($mid);
+ $mid = sha1_hex($mid);
+ ($x2, $x38) = ($mid =~ /\A([a-f0-9]{2})([a-f0-9]{38})\z/);
+ }
+ "$x2/$x38";