Review messages filtered from original import

[rpcross]

During the "new" Mail Archive deployment, messages not included in the legacy MHonArc web archive were excluded from the archive. (saved to _filtered).

A recent RT issue reported missing archives for ngtrans list. These were subsequently imported from the _filtered directory.

Robert has identified other lists that may have been filtered and require review.

for g in Group.objects.filter(list_archive__startswith="ftp://ftp.ietf.org"):
... print(g.acronym, g.list_archive)
...
nat ftp://ftp.ietf.org/ietf-mail-archive/nat/
cat ftp://ftp.ietf.org/ietf-mail-archive/cat/
frnetmib ftp://ftp.ietf.org/ietf-mail-archive/frnetmib/
idmr ftp://ftp.ietf.org/ietf-mail-archive/idmr/
ion ftp://ftp.ietf.org/ietf-mail-archive/ion
ngtrans ftp://ftp.ietf.org/ietf-mail-archive/ngtrans/
secsh ftp://ftp.ietf.org/ietf-mail-archive/secsh/
malloc ftp://ftp.ietf.org/ietf-mail-archive/malloc/
ecm ftp://ftp.ietf.org/ietf-mail-archive/
nits ftp://ftp.ietf.org/ietf-mail/archive/nits
saad ftp://ftp.ietf.org/ietf-mail-archive/saad