Its comment says "for msh only".
#define set_unseen(mp,msgnum) \
bvector_set (msgstat(mp, msgnum), SELECT_UNSEEN)
#define set_unseen(mp,msgnum) \
bvector_set (msgstat(mp, msgnum), SELECT_UNSEEN)
-/* for msh only */
-#define set_deleted(mp,msgnum) bvector_set (msgstat(mp, msgnum), DELETED)
-
#define in_sequence(mp,seqnum,msgnum) \
bvector_at (msgstat(mp, msgnum), FFATTRSLOT + seqnum)
#define clear_sequence(mp,seqnum,msgnum) \
#define in_sequence(mp,seqnum,msgnum) \
bvector_at (msgstat(mp, msgnum), FFATTRSLOT + seqnum)
#define clear_sequence(mp,seqnum,msgnum) \