Jun 12 05:20:03 Host1db1 sendmail[1128]: [ID 801593 mail.warning] l5BMK3r6001127: forward /oracle/product/9.2.0.1.0/.forward.Host1db1+
: World writable directory
Jun 12 05:20:03 Host1db1 sendmail[1128]: [ID 801593 mail.warning] l5BMK3r6001127: forward /oracle/product/9.2.0.1.0/.forward+: World
writable directory
Jun 12 05:20:03 Host1db1 sendmail[1128]: [ID 801593 mail.warning] l5BMK3r6001127: forward /oracle/product/9.2.0.1.0/.forward.Host1db1:
World writable directory
Jun 12 05:20:03 Host1db1 sendmail[1128]: [ID 801593 mail.warning] l5BMK3r6001127: forward /oracle/product/9.2.0.1.0/.forward: World w
ritable directory
Jun 12 05:20:03 Host1db1 sendmail[1128]: [ID 801593 mail.info] l5BMK3r6001127: to=<oracle@Host1db1.tmtoa.com>, ctladdr=<oracle@
Host1db1.tmt.toyota.co.th> (101/100), delay=00:00:00, xdelay=00:00:00, mailer=local, pri=30832, relay=local, dsn=2.0.0, stat=Sent
Jun 12 05:20:05 Host1db1 sendmail[1141]: [ID 801593 mail.info] l5BMK5MQ001141: from=oracle, size=286, class=0, nrcpts=1, msgid=<20070
6112220.l5BMK5MQ001141@Host1db1.tmtoa.com>, relay=oracle@localhost
Jun 12 05:20:05 Host1db1 sendmail[1142]: [ID 801593 mail.info] l5BMK5r6001142: from=<oracle@Host1db1.tmtoa.com>, size=577, clas
s=0, nrcpts=1, msgid=<200706112220.l5BMK5MQ001141@Host1db1.tmtoa.com>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1]
Jun 12 05:20:05 Host1db1 sendmail[1141]: [ID 801593 mail.info] l5BMK5MQ001141: to=oracle, ctladdr=oracle (101/100), delay=00:00:00, x
delay=00:00:00, mailer=relay, pri=30286, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (l5BMK5r6001142 Message accepted for de
livery)


I found these errors in /var/log so I don't know why it occurs and how to solve it,

Thank u in advance

Here is a useful article on this subject, take a look, and hopefully this will resolve your problem. There are few workarounds suggested, hence the link.