[Dovecot] connecting postfix with dovecot trouble

[André Höpner]

Hello listmembers,

we have some trouble connecting postfix to dovecot. 
after a lot of hours the transport and delivery is
working but dovecot can't get the correct user.

postmap -q some.user at domain.com ldap:/etc/postfix/ldap-aliases.cf first
returns: someuser 

The mailbox someuser exists and i can login with this
user on imap and i can deliver directly using deliver -d
but on mail delivery thrue postfix dovecot is not looking
for someuser. It looks for someuser at host.domain.com.

---8<------
May  3 16:18:42 mail postfix/pickup[24686]: C94251DB23E: uid=0 from=<root>
May  3 16:18:42 mail postfix/cleanup[24769]: C94251DB23E:
message-id=<20070503161842.C94251DB23E at host.domain.com>
May  3 16:18:42 mail postfix/qmgr[24544]: C94251DB23E:
from=<root at host.domain.com>, size=322, nrcpt=1 (queue active)
May  3 16:18:42 mail dovecot: auth(default): master in: USER    1
someuser at host.domain.com service=deliver
May  3 16:18:42 mail dovecot: auth(default): ldap(someuser at host.domain.com):
user search: base=dc=domain,dc=com scope=subtree
filter=(&(objectClass=posixAccount)(uid=someuser at host.domain.com))
fields=mail,homeDirectory
May  3 16:18:42 mail dovecot: auth(default): master out: USER   1
someuser at host.domain.com home=/var/mail/dovecot/someuser uid=100 gid=12
May  3 16:18:42 mail postfix/pipe[24772]: C94251DB23E:
to=<someuser at host.domain.com>, orig_to=<some.user at domain.com>,
relay=dovecot, delay=0.04, delays=0.02/0.01/0/0.02, dsn=2.0.0, status=sent
(delivered via dovecot service)
May  3 16:18:42 mail postfix/qmgr[24544]: C94251DB23E: removed
---8<------

It seems that postfix or dovecot appends the hostname to
the mailboxname. But i cant figure out which of both.
If i change the uid to someuser at hostname.domain.com on
ldap-server anything works fine. how can i fix this?

i dont know if anyone needs config files for diagnostic.
if so - please tell me and i post the needed informations.

best regards
Andre Hoepner