crash ??......

시스템이 자꾸 하루에 한번씩 다운이 됩니다....이유는 먼지 몰겠는데,
다운되면 재부팅하고 그러거든요.....
아래에서 crash 라는게 도대체 먼지....??..
다운되는 이유는 먼지 궁금합니다...
혹시, 저희서버가 스팸서버로 사용해서 트래픽이 엄청걸려서 다운되는 걸까요?
ps -ax해보면 샌드메일관련데몬이 많이 떠있습니다.

]# last|more
root tty1 Mon Jun 24 15:51 still logged in
reboot system boot 2.4.13-1hl Mon Jun 24 15:40 (05:15)
root pts/0 Mon Jun 24 07:06 - 07:18 (00:12)
root pts/0 Mon Jun 24 07:06 - 07:06 (00:00)
root tty1 Mon Jun 24 07:05 - crash (08:35)
reboot system boot 2.4.13-1hl Mon Jun 24 07:04 (13:51)
root pts/0 Sun Jun 23 14:50 - 14:51 (00:00)
root pts/0 Sun Jun 23 14:50 - 14:50 (00:00)
root tty1 Sun Jun 23 14:49 - crash (16:14)
reboot system boot 2.4.13-1hl Sun Jun 23 14:49 (1+06:07)
root tty1 Sun Jun 23 06:30 - crash (08:18)
reboot system boot 2.4.13-1hl Sun Jun 23 06:29 (1+14:26)
root tty1 Sat Jun 22 17:04 - crash (13:25)
reboot system boot 2.4.13-1hl Sat Jun 22 17:03 (2+03:52)
root tty1 Sat Jun 22 07:59 - crash (09:04)
reboot system boot 2.4.13-1hl Sat Jun 22 07:58 (2+12:57)
root tty1 Fri Jun 21 22:01 - crash (09:57)
reboot system boot 2.4.13-1hl Fri Jun 21 22:00 (2+22:55)
root pts/0 Fri Jun 21 20:27 - crash (01:33)
root pts/0 Fri Jun 21 20:27 - 20:27 (00:00)
root pts/0 Fri Jun 21 07:27 - 08:08 (00:40)
root pts/0 Fri Jun 21 07:27 - 07:27 (00:00)

ps -ax 하면 샌드메일관련 메일이 많이 떠있습니다..
누가 도대체 하루종일 메일서버이용하는걸까요?
스팸인가요..??궁금합니다... 스팸이라면 대책도 좀 부탁드립니다...
]#ps -ax
16448 ? S 0:00 sendmail: server ipd50ad02c.speed.planet.nl [213.10.208.44] child wait
16459 ? S 0:01 sendmail: server ts022d13.phx-az.concentric.net [208.176.172.73] child wait
16470 ? S 0:00 sendmail: ./g5OD1fR16452 mx09.hotmail.com.: client RCPT
16471 ? S 0:00 sendmail: ./g5OD2ZR16471 ipd50ad02c.speed.planet.nl [213.10.208.44]: RCPT To:16480 ? S 0:00 in.telnetd: 211.229.130.121
16481 ? S 0:00 login -- park
16486 ? S 0:00 sendmail: server 1Cust223.tnt25.dfw9.da.uu.net [67.234.6.223] child wait
16487 pts/0 S 0:00 -bash
16523 ? S 0:00 sendmail: g5OD2wR16523 1Cust223.tnt25.dfw9.da.uu.net [67.234.6.223]: MAIL From
16529 ? S 0:00 sendmail: server 1Cust223.tnt25.dfw9.da.uu.net [67.234.6.223] child wait
16532 ? S 0:00 sendmail: g5OD3BR16532 1Cust223.tnt25.dfw9.da.uu.net [67.234.6.223]: MAIL From
16534 ? S 0:00 sendmail: ./g5OD2vR16522 relay.corp.visto.com.: user open
16538 ? S 0:00 sendmail: ./g5OD3DR16535 mx02.comstar.net.: client greeting
16543 ? S 0:00 sendmail: ./g5OD2YR16468 mx2.hanmail.net.: client DATA 354
16545 ? S 0:00 sendmail: mx07.hotmail.com.: idle
16549 ? S 0:00 sendmail: ./g5OD3DR16536 mail.industriesjohnlewis.com.: user open
16551 ? S 0:00 sendmail: ./g5OD3TR16546 mailin-04.mx.aol.com.: client DATA status
16555 ? S 0:00 sendmail: ./g5OD3bR16553 mailin-03.mx.aol.com.: user open
16556 ? S 0:00 sendmail: g5OD3kR16556 ts022d13.phx-az.concentric.net [208.176.172.73]: RCPT TO:16558 pts/0 R 0:00 ps -ax