virtual domains

[Renzetti Federico]

Hi all,
this is my first mail to the list.
I'm using cyrus-imapd-2.2.10-3 and I have some problems to configure 
virtual domains.
this is my imapd.conf:
...
configdirectory: /var/lib/imap
partition-default: /var/spool/imap
admins: cyrus postmaster
sievedir: /var/lib/imap/sieve
sendmail:  /var/qmail/bin/sendmail
hashimapspool: true
sasl_pwcheck_method: saslauthd
sasl_mech_list: PLAIN
virtdomains: userid
defaultdomain: domain.com
...
My user-backend is LDAP and user-uid is something like "user at domain.com".
When I try to login via IMAP with user at domain.com in ldap.log I see 
(filter=user) and not (filter=user at domain.com) so I can't login.
Anyone can help me?
Thanks in advance.

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