Strange log messages on a `closed" relay + few more...

Oct 16 22:40:17 mail sm-mta[34495]: l9GGeEvM034495: to= return-62-akstcmydomainmnsdgs=domain.com@apetitoenlinea.com> ,
delay=00:00:03, xdelay=00:00:03, mailer=esmtp, pri=30000,
relay=mail.jocote.com. [64.8.120.7], dsn=2.0.0, stat=Sent (ok
1192552819 qp 16821)
....
Oct 16 22:40:43 mail sm-mta[34536]: l9GGedBi034536:
to=, delay=00:00:04, xdelay=00:00:04,
mailer=esmtp, pri=30000, relay=mx1.bne.server-mail.com.
[203.147.175.1], dsn=2.0.0, stat=Sent (14gg1Y00102JHHt0000000 mail
accepted for delivery)
....
Oct 16 22:41:28 mail sm-mta[34616]: l9GGfR8v034616:
to=, delay=00:00:01, xdelay=00:00:01,
mailer=esmtp, pri=30000, relay=komet.ru. [80.253.0.2], dsn=2.0.0,
stat=Sent ( <200710161641.l9GGfR8v034616@mail.domain.com> Queued mail
for delivery)

It's sendmail + dbmail + sasl2 setup, open relay tests show that no
open relay is available.
However... some things seem to come through... - how ?

Also earlier this day I've got a spam mail sent to something like
xfvbjasdf@mydomain.com... needless to say that user/alias `xfvbj....'
doesn't exist on the server.


More questions:

1. I need to setup the server so that even users sending mail from
user@mydomain to user2@mydomain should be authenticated but the
following line doesn't work for me
define(`confAUTH_OPTIONS', `Ay')dnl
At present they can easily send emails from any IP without any
authentication if they are sending it `locally'
Authentication works in all other cases (user@mydomain --->
user@otherdomain...)

2. atm when I try sendmail -bt:
> mail# sendmail -bt
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter