잘되던 폼메일이 안됩니다. 어디를 체크해봐야할까요?

서버a:웹서버
서버b:DB,dns,메일

이렇게 사용중입니다.

a서버에서 폼메일로 메일이 잘 발송되었는데

sendmail 환경파일을 잘못건드린것인지 메일폼메일이 전송이 안되고

clientqueue에 쌓이기만하고 보내지지 않습니다  smtp는 사용중입니다. 메일서버(b)쪽에는

아이피로 릴레이하다가 아이디,비번 인증방식으로 수정하였고 스팸어세신도

설치하였습니다. 이과정에서 무언가 잘못되었는지.. 어디를 체크해봐야할가요?

일부 로그를 보면

Jan 11 13:19:25 MNS2 sendmail[13958]: l0B4JPbZ013958: to=webmaster@mnshome.com, ctladdr=nobody (99/99), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=36137, relay=[127.0.0.1] [127.0.0.1], dsn=5.1.1, stat=User unknown
Jan 11 13:19:25 MNS2 sendmail[13960]: l0B4JPjc013960: from=<nobody@localhost.localdomain>, size=6137, class=0, nrcpts=0, bodytype=8BITMIME, proto=ESMTP, daemon=MTA, relay=MNS2 [127.0.0.1]
Jan 11 13:19:25 MNS2 sendmail[13958]: l0B4JPbZ013958: l0B4JPba013958: DSN: User unknown
Jan 11 13:19:25 MNS2 sendmail[13960]: l0B4JPje013960: from=<>, size=8185, class=0, nrcpts=1, msgid=<200701110419.l0B4JPba013958@localhost.localdomain>, bodytype=8BITMIME, proto=ESMTP, daemon=MTA, relay=MNS2 [127.0.0.1]
Jan 11 13:19:25 MNS2 sendmail[13958]: l0B4JPba013958: to=nobody, delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=37161, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (l0B4JPje013960 Message accepted for delivery)
Jan 11 13:19:25 MNS2 sendmail[13961]: l0B4JPje013960: to=root, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=38397, dsn=2.0.0, stat=Sent
Jan 11 13:19:25 MNS2 sendmail[13963]: l0B4JP7W013963: from=nobody, size=6150, class=0, nrcpts=1, msgid=<200701110419.l0B4JP7W013963@localhost.localdomain>, bodytype=8BITMIME, relay=nobody@localhost
Jan 11 13:19:25 MNS2 sendmail[13965]: l0B4JP1A013965: from=<nobody@localhost.localdomain>, size=6381, class=0, nrcpts=1, msgid=<200701110419.l0B4JP7W013963@localhost.localdomain>, bodytype=8BITMIME, proto=ESMTP, daemon=MTA, relay=MNS2 [127.0.0.1]
Jan 11 13:19:25 MNS2 sendmail[13963]: l0B4JP7W013963: to=kshan8854@kr.yahoo.com, ctladdr=nobody (99/99), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=36150, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (l0B4JP1A013965 Message accepted for delivery)
Jan 11 13:20:25 MNS2 sendmail[13967]: l0B4JP1A013965: to=<kshan8854@kr.home.yahoo4.akadns.net>, ctladdr=<nobody@localhost.localdomain> (99/99), delay=00:01:00, xdelay=00:01:00, mailer=esmtp, pri=36381, relay=kr.home.yahoo4.akadns.net. [203.212.171.159], dsn=4.0.0, stat=Deferred: Connection timed out with kr.home.yahoo4.akadns.net.

일단 로컬쪽은 릴레이되도록 설정해 놓았는데 로그 첫줄에 보면 있는 계정인데
없는유저라고  릴레이가 안되는것 같은데 왜 그런지 아시는분 답변좀 부탁드려요