no open relay and log shows a someone got through !?

[progressdll]

Hi,

our qmail server is no open relay and we are only accepting mail for 2 domains. This works (untill now) perfect.

I also don't allow mail for not local users to be accepted ( via database check )

But this some spammer got in my logs. Trying to send mail from a domain that i don't want to able to send.

@daum.net => this is a know spam source it seems

What am i leaving open for them to enter?

A strange side effect that i witnessed twice is that on the day that i have this output in the logs , i have a CNAME lookup failure. Don't know if there is a connection between these 2 issues but i had them twice , each time when i found the spammer in my logs

log output
Jun 24 06:20:00 linuxnol2004 qmail: 1119586800.388203 new msg 121064
Jun 24 06:20:00 linuxnol2004 qmail: 1119586800.388302 info msg 121064: bytes 793 from <iqdojotosu283@daum.net> qp 23655 uid 1002
Jun 24 06:20:00 linuxnol2004 qmail: 1119586800.402620 starting delivery 6328: msg 121064 to remote smtphunter55@daum.net
Jun 24 06:20:00 linuxnol2004 qmail: 1119586800.402719 status: local 0/10 remote 1/20