or download this
$ perl mailbox_parser.pl /home/zwon/Mail/FreeBSD-security | head -n 20
00000 => 0000000000 => FreeBSD Security Advisory FreeBSD-SA-04:03.jail
...
00017 => 0000151053 => FreeBSD Security Advisory FreeBSD-SA-05:01.teln
+et
00018 => 0000160935 => FreeBSD Security Advisory FreeBSD-SA-05:02.send
+file
00019 => 0000170195 => FreeBSD Security Advisory FreeBSD-SA-05:03.amd6
+4