RE: [exim] Not freezing "unknown user"?

> That's a bounce generated by your own host. What was the mail which
> _caused_ the bounce?

Sorry, my mistake.

Feb 8 14:39:57 nvoweb exim: 2005-02-08 14:39:57 1CyVau-0002q3-Fi <=
Mailer-Daemon@??? H=ncc3.infomail.es (infomail.es)
[195.235.39.5] P=esmtp S=2547
Feb 8 14:39:57 nvoweb exim: 2005-02-08 14:39:57 1CyVau-0002q3-Fi **
burtongregg43@??? R=relay_router_nwl T=local_smtp: SMTP error from
remote mailer after RCPT TO:<burtongregg43@???>: host 192.168.221.211
[192.168.221.211]: 550 5.1.1 User unknown

There is a incoming mail to a nonexistent router.

The Exim does a callout and our exchange replies "User unknown." And as
far I can tell, that should not generate a bounce from my system, since
the ACL-call out should kill the transaction before it actually becomes
a mail?