sendmail 무슨 에러인지좀 알려주세요

Apr 8 15:20:48 tplus-mail sendmail[1476]: h386KmDG001476: from=<root@tplus.co.kr>, size=329, class=0, nrcpts=1, msgid=<20030
4080620.h386Km98001475@tplus.co.kr>, proto=ESMTP, daemon=MTA, relay=localhost [127.0.0.1]
Apr 8 15:20:49 tplus-mail sendmail[1478]: h386KmDG001476: to=<coco100@hananet.net>, ctladdr=<root@tplus.co.kr> (0/1), delay=
00:00:01, xdelay=00:00:00, mailer=esmtp, pri=120324, relay=hananet.net, dsn=5.1.2, stat=Host unknown (Name server: hananet.ne
t: host not found)
Apr 8 15:20:49 tplus-mail sendmail[1478]: h386KmDG001476: h386KnDG001478: DSN: Host unknown (Name server: hananet.net: host not found)
Apr 8 15:20:49 tplus-mail sendmail[1475]: h386Km98001475: to=coco100@hananet.net, ctladdr=root (0/1), delay=00:00:01, xdelay
=00:00:01, mailer=relay, pri=30057, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (h386KmDG001476 Message accepted for
delivery)
Apr 8 15:20:49 tplus-mail sendmail[1479]: h386KnDG001478: Warning: program /usr/lib/mail.local unsafe: Group writable direct
ory
Apr 8 15:20:49 tplus-mail sendmail[1478]: h386KnDG001478: to=<root@tplus.co.kr>, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=31561, dsn=2.0.0, stat=Sent
Apr 8 15:21:19 tplus-mail sendmail[1482]: dangerous permissions=40755 on queue directory /var/spool/clientmqueue/
Apr 8 15:21:19 tplus-mail sendmail[1482]: h386LJF8001482: from=root, size=57, class=0, nrcpts=1, msgid=<200304080621.h386LJF
8001482@tplus.co.kr>, relay=root@localhost
Apr 8 15:21:20 tplus-mail sendmail[1483]: h386LKDG001483: from=<root@tplus.co.kr>, size=327, class=0, nrcpts=1, msgid=<20030
4080621.h386LJF8001482@tplus.co.kr>, proto=ESMTP, daemon=MTA, relay=localhost [127.0.0.1]
Apr 8 15:21:20 tplus-mail sendmail[1482]: h386LJF8001482: to=dennis_min, ctladdr=root (0/1), delay=00:00:01, xdelay=00:00:00
, mailer=relay, pri=30048, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (h386LKDG001483 Message accepted for delivery)
Apr 8 15:21:20 tplus-mail sendmail[1484]: h386LKDG001483: forward /export/home/dennis_min/.forward.tplus-mail+: Group writab
le directory
Apr 8 15:21:20 tplus-mail sendmail[1484]: h386LKDG001483: forward /export/home/dennis_min/.forward+: Group writable director
y
Apr 8 15:21:20 tplus-mail sendmail[1484]: h386LKDG001483: forward /export/home/dennis_min/.forward.tplus-mail: Group writabl
e directory
Apr 8 15:21:20 tplus-mail sendmail[1484]: h386LKDG001483: forward /export/home/dennis_min/.forward: Group writable directory
Apr 8 15:21:20 tplus-mail sendmail[1485]: h386LKDG001483: Warning: program /usr/lib/mail.local unsafe: Group writable direct
ory
Apr 8 15:21:20 tplus-mail sendmail[1484]: h386LKDG001483: to=<dennis_min@tplus.co.kr>, ctladdr=<root@tplus.co.kr> (0/1), del
ay=00:00:00, xdelay=00:00:00, mailer=local, pri=30538, dsn=2.0.0, stat=Sent
~
내부로 보내면 잘가거든요 그런데 외부로 보내면 호스트를 못 찾는다고 나오는거같은데
그럼 dns설정에 문제가 있어서 그런가요 아님 sendmail설정부분에서 문제가 있는건가요??
어느쪽에 문제가 있는것만이라도 알려주세요 아 정말 힘들어 미치겠어요유ㅜ.ㅜ
부탁드립니다.