Shared folders and Outlook

[dimon at intellinetinc.com]

> As far as I know, sendmail cannot be configured to accept +mbox at domain
> without
> hacking the .cf file.  I looked briefly at modifying the m4 definitions and
> then
> just gave up and used bb+mbox at domain by setting postuser.
> 

I tried bb+mbox at domain which is bb+test at intellinet.ab.ca in my case
I added postuser: dd to my imapd.conf but it still doesn't work:
Apr 25 15:27:52 mail sm-mta[7462]: h3PLRnWF007454: 
to=<bb+test at intellinet.ab.ca>, delay=00:00:03, xdelay=00:00:00, mailer=cyrusv2, 
pri=30363, relay=localhost, dsn=5.7.1, stat=User unknown
Apr 25 15:27:52 mail sm-mta[7462]: h3PLRnWF007454: h3PLRqWF007462: DSN: User 
unknown

What else could be wrong?
Do I have to configure sendmail especially for that?

Dmitry