스팸메일을 어떻게 막아야 할까요?

find ./ -type f -exec grep 'Subject' {} /dev/null ;

이렇게 검색을 해보니 아래와 같이 끝도없이 나오네요.

전에 스팸메일 발송된다고 idc에서 연락받고 데몬을 내리고 리눅스 서버관리 실무 바이블을 보고 몇가지 보안설정을 일단 해놓긴 했는데 sendmail 데몬만 올리면 문제가 발생합니다. 어떻게해야 할까요

./qfkBMLnRm8026470:H??Subject: eBay Registration On Hold
./qfkBILcDDW028738:H??Subject: eBay Registration On Hold
./qfkBL0ulxh011510:H??Subject: eBay Registration On Hold
./qfkBN9amr6020221:H??Subject: eBay Registration On Hold
./qfkBKNHphr005095:H??Subject: eBay Registration On Hold
./qfkBG8tVJb018317:H??Subject: eBay Registration On Hold
./qfkBHLm8qe029757:H??Subject: eBay Registration On Hold
./qfkBNCRq0X004678:H??Subject: eBay Registration On Hold
./qfkBMFKfla027016:H??Subject: eBay Registration On Hold
./qfkBHDqJYF024112:H??Subject: eBay Registration On Hold
./qfkBMMZr6t000856:H??Subject: eBay Registration On Hold
./qfkBFLPaYe001881:H??Subject: eBay Registration On Hold
./qfkBJLcTr0029539:H??Subject: eBay Registration On Hold
./qfkBN8WSZ9012001:H??Subject: eBay Registration On Hold
./qfkBMFhI4D028338:H??Subject: eBay Registration On Hold
./qfkBKMnLJE001924:H??Subject: eBay Registration On Hold
./qfkBFJ8lSN021954:H??Subject: eBay Registration On Hold
./qfkBGA6nrF025446:H??Subject: eBay Registration On Hold
./qfkBMG2agc029563:H??Subject: eBay Registration On Hold
./qfkBN9l1B4021586:H??Subject: eBay Registration On Hold
./qfkBGBRoIR000568:H??Subject: eBay Registration On Hold
./qfkBFMSnZO010478:H??Subject: eBay Registration On Hold
./qfkBG73p1g010290:H??Subject: eBay Registration On Hold
./qfkBEITFcT029181:H??Subject: eBay Registration On Hold
./qfkBK5dMdM029742:H??Subject: eBay Registration On Hold
./qfkBG8DGOd014279:H??Subject: eBay Registration On Hold
./qfkBEHuQOc027131:H??Subject: eBay Registration On Hold
./qfkBHMHs1W002293:H??Subject: eBay Registration On Hold
./qfkBJMXkcc002967:H??Subject: eBay Registration On Hold
./qfkBH2dX79010536:H??Subject: eBay Registration On Hold
./qfkBK5J0Qm028589:H??Subject: eBay Registration On Hold
./qfkBNAtM52029171:H??Subject: eBay Registration On Hold
./qfkBH95Qu9002843:H??Subject: eBay Registration On Hold
./qfkBL2C16t015733:H??Subject: eBay Registration On Hold
./qfkBNIitrK031832:H??Subject: eBay Registration On Hold
./qfkBG5A7dh004185:H??Subject: eBay Registration On Hold
./qfkBJH8MHp006791:H??Subject: eBay Registration On Hold
./qfkBNKCiXA009226:H??Subject: eBay Registration On Hold
./qfkBHBsQb9017029:H??Subject: eBay Registration On Hold
./qfkBFLXlJR003083:H??Subject: eBay Registration On Hold
./qfkBJ7pmFq006722:H??Subject: eBay Registration On Hold
./qfkBJN8LhC006603:H??Subject: eBay Registration On Hold
./qfkBLLpFUx022300:H??Subject: eBay Registration On Hold
./qfkBHKmTJR020247:H??Subject: eBay Registration On Hold
./qfkBJM3aKU032563:H??Subject: eBay Registration On Hold
./qfkBEHx64Q027239:H??Subject: eBay Registration On Hold
./qfkBELTBZX012109:H??Subject: eBay Registration On Hold
./qfkBNHj8Ae027261:H??Subject: eBay Registration On Hold
./qfkBN2JqmV022306:H??Subject: eBay Registration On Hold
./qfkBKMGnAc030513:H??Subject: eBay Registration On Hold
./qfkBEA6V3S000334:H??Subject: eBay Registration On Hold
./qfkBNKhaCn012406:H??Subject: eBay Registration On Hold
./qfkBFMqoLL013250:H??Subject: eBay Registration On Hold
./qfkBL9svr5009688:H??Subject: eBay Registration On Hold
./qfkBG9hwWT023007:H??Subject: eBay Registration On Hold
./qfkBHMlYXo007520:H??Subject: eBay Registration On Hold
./qfkBLLfdGa021097:H??Subject: eBay Registration On Hold
./qfkBGMP63D018530:H??Subject: eBay Registration On Hold
./qfkBNJrQja007482:H??Subject: eBay Registration On Hold
./qfkBG9C3va020166:H??Subject: eBay Registration On Hold
./qfkBJH7UVO006768:H??Subject: eBay Registration On Hold
./qfkBECB8E7007289:H??Subject: eBay Registration On Hold