High Server Load, over 18

[synax]

Every day at the same time we have a mailing list that runs, it has almost 4000 clients on the list and lately the server has been crashing shortly after it starts running. From what I can tell, the script we installed is not the issue, it is either EXIM or MailScanner. I ran a ps ux during the high load, I would post it below but it is to Large. I will post the TOP below though. Any assistance would be greatly appreciated.

-TOP-
TOP-
3:34pm up 15:01, 1 user, load average: 17.57, 10.34, 4.46
305 processes: 287 sleeping, 18 running, 0 zombie, 0 stopped
CPU states: 59.4% user, 21.6% system, 0.0% nice, 18.8% idle
Mem: 505868K av, 457004K used, 48864K free, 0K shrd, 34452K buff
Swap: 2096472K av, 110412K used, 1986060K free 179380K cached

PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND
23746 root 9 0 204 204 24 S 99.9 0.0 0:00 exim
23877 root 9 0 2136 2136 1624 S 99.9 0.4 0:00 exim
25645 root 9 0 1260 1260 1080 S 99.9 0.2 0:00 exim
970 mailnull 9 0 9716 132 0 S 11.9 0.0 0:48 MailScanner
2162 mailnull 9 0 9812 212 0 S 10.5 0.0 0:44 MailScanner
25984 mailnull 17 0 11976 11M 596 R 5.7 2.3 0:00 clamscan
26028 mailnull 17 0 8484 8484 596 R 4.3 1.6 0:00 clamscan
26082 mailnull 16 0 748 748 592 R 1.1 0.1 0:00 clamscan
1206 named 9 0 13476 12M 832 S 0.9 2.4 0:45 named
25381 root 11 0 1288 1288 848 R 0.5 0.2 0:00 top
24746 root 9 0 208 208 24 S 0.3 0.0 0:00 exim
26081 root 14 0 1264 1264 1080 S 0.3 0.2 0:00 exim
20 root 9 0 0 0 0 SW 0.1 0.0 0:12 kjournald
866 root 10 0 2404 1352 772 S 0.1 0.2 0:01 chkservd
1512 mysql 9 0 14864 3896 1040 S 0.1 0.7 0:01 mysqld
2296 root 9 0 3828 1588 640 S 0.1 0.3 0:00 eximstats
19849 dynamics 12 0 1824 1824 564 S 0.1 0.3 0:00 domail
26001 root 9 0 1264 1264 1080 S 0.1 0.2 0:00 exim
26058 root 13 0 1264 1264 1080 S 0.1 0.2 0:00 exim
26086 root 14 0 1260 1260 1080 S 0.1 0.2 0:00 exim
26101 root 16 0 1060 1060 940 S 0.1 0.2 0:00 sh
26102 mailnull 13 0 1416 1416 1204 R 0.1 0.2 0:00 sendmail
26103 root 16 0 708 708 576 R 0.1 0.1 0:00 ps
1 root 7 0 100 76 52 S 0.0 0.0 0:04 init
2 root 9 0 0 0 0 SW 0.0 0.0 0:00 keventd
3 root 9 0 0 0 0 SW 0.0 0.0 0:00 kapmd
4 root 19 19 0 0 0 SWN 0.0 0.0 0:01 ksoftirqd_CPU0
5 root 9 0 0 0 0 SW 0.0 0.0 0:00 kswapd
6 root 9 0 0 0 0 SW 0.0 0.0 0:00 kscand/DMA
7 root 9 0 0 0 0 SW 0.0 0.0 0:25 kscand/Normal
8 root 9 0 0 0 0 SW 0.0 0.0 0:00 kscand/HighMem
9 root 9 0 0 0 0 SW 0.0 0.0 0:00 bdflush
10 root 9 0 0 0 0 SW 0.0 0.0 0:00 kupdated
11 root -1 -20 0 0 0 SW< 0.0 0.0 0:00 mdrecoveryd
17 root 9 0 0 0 0 SW 0.0 0.0 0:00 scsi_eh_0
76 root 9 0 0 0 0 SW 0.0 0.0 0:00 khubd
273 root 9 0 0 0 0 SW 0.0 0.0 0:00 kjournald
727 root 9 0 228 200 152 S 0.0 0.0 0:04 syslogd
731 root 9 0 52 4 0 S 0.0 0.0 0:00 klogd
822 nobody 8 0 712 220 124 S 0.0 0.0 0:00 proftpd
832 root 9 0 240 80 0 S 0.0 0.0 0:00 sshd
847 root 9 0 232 152 84 S 0.0 0.0 0:00 xinetd
962 root 12 0 1676 112 64 S 0.0 0.0 0:19 httpd
989 root 8 0 124 100 56 S 0.0 0.0 0:00 crond
1235 root 8 0 2988 840 428 S 0.0 0.1 0:00 cpsrvd
1241 root 18 19 4820 916 60 S N 0.0 0.1 0:06 cpanellogd
1247 root 9 0 2220 872 444 S 0.0 0.1 0:04 cppop
1251 nobody 9 0 884 4 0 S 0.0 0.0 0:00 entropychat
1256 nobody 9 0 236 4 0 S 0.0 0.0 0:00 melange
1281 cpanel 9 0 324 248 24 S 0.0 0.0 0:00 stunnel-4.04loc
1289 mailman 9 0 2740 4 0 S 0.0 0.0 0:00 mailmanctl
1296 mailman 9 0 3032 800 272 S 0.0 0.1 0:00 python2
1297 mailman 9 0 3056 872 292 S 0.0 0.1 0:00 python2
1298 mailman 9 0 3036 888 272 S 0.0 0.1 0:00 python2
1301 mailman 9 0 3032 940 272 S 0.0 0.1 0:00 python2
1302 mailman 9 0 3076 1072 272 S 0.0 0.2 0:00 python2
1303 mailman 9 0 3096 1168 272 S 0.0 0.2 0:00 python2

[Promethyl]

Can you try using nice to lower exim's priority? Until it's figured out, it's going to give you problems...

Is there a thread priority value in the conf file?