Thankyou for your reply:
After i checked the login, it queries the database, which is empty. It seems that during the install the inserts / right of the PGSQL database are messed up.
The SQL structure is there, but there are no rows inserted, and every user except postgres had no rights to read any database. After i've put these rights on every account i got this from iredmail:
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] Traceback (most recent call last):
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/application.py", line 235, in process
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] return p(lambda: process(processors))
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/session.py", line 82, in _processor
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] self._cleanup()
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/session.py", line 168, in _cleanup
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] self.store.cleanup(timeout)
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/session.py", line 315, in cleanup
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] self.db.delete(self.table, where="$last_allowed_time > atime", vars=locals())
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/db.py", line 906, in delete
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] db_cursor = self._db_cursor()
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/db.py", line 566, in _db_cursor
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] return self.ctx.db.cursor()
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/db.py", line 507, in _getctx
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] self._load_context(self._ctx)
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/db.py", line 518, in _load_context
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] ctx.db = self._connect(self.keywords)
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/db.py", line 960, in _connect
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] conn = DB._connect(self, keywords)
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] File "/usr/lib/python2.6/site-packages/web/db.py", line 546, in _connect
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] return self.db_module.connect(**keywords)
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx] OperationalError: FATAL: password authentication failed for user "iredadmin"
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx]
[Tue Sep 11 15:14:05 2012] [error] [client xxxxxxxxxx]
[Tue Sep 11 15:14:58 2012] [error] Exception KeyError: KeyError(-1208215728,) in <module 'threading' from '/usr/lib/python2.6/threading.pyc'> ignored
[Tue Sep 11 15:14:59 2012] [error] Exception KeyError: KeyError(-1208215728,) in <module 'threading' from '/usr/lib/python2.6/threading.pyc'> ignored
[Tue Sep 11 15:15:07 2012] [error] Exception KeyError: KeyError(-1208215728,) in <module 'threading' from '/usr/lib/python2.6/threading.pyc'> ignored