Dec 16 15:49:54 sendmail[3312]: mBG6ns6C003312: mBG6ns6D003312: return to sender: Service unavailable
Dec 16 15:49:54 sendmail[3312]: mBG6ns6D003312: to=postmaster, delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=47576, relay=[127.0.0.1], dsn=5.0.0, stat=Service unavailable
Dec 16 15:49:54 sendmail[3312]: mBG6ns6C003312: Losing ./qfmBG6ns6C003312: savemail panic
Dec 16 15:49:54 sendmail[3312]: mBG6ns6C003312: SYSERR(nobody): savemail: cannot save rejected email anywhere

===> hosts.allow 파일 에 127.0.0.1 추가

127.0.0.1 이 등록되어 있지 않으면 메일 발송에 문제가 발생 된다.