Mailing: Temporary lookup failure

I've still the problem, that I can't send and receive Mails.
During sending:

Message not sent. Server replied:
Requested action aborted: error in processing
451 4.3.0 <[email protected]>: Temporary lookup failure
Shown in squirrelmail

I found some more mistakes:

Jun 26 21:01:01 h2101310 postfix/trivial-rewrite[2468]: warning: hash:/var/lib/mailman/data/transport-mailman is unavailable. open database /var/lib/mailman/data/transport-mailman.db: Invalid argument

But this belongs to the mailman...
Next:

Jun 26 21:01:01 h2101310 postfix/trivial-rewrite[2468]: warning: hash:/var/lib/mailman/data/transport-mailman lookup error for "[email protected]"
Jun 26 21:01:01 h2101310 postfix/trivial-rewrite[2468]: warning: transport_maps lookup failure
Jun 26 21:01:01 h2101310 postfix/smtpd[2466]: NOQUEUE: reject: RCPT from mx2.slc.paypal.com[173.0.84.227]: 451 4.3.0 <[email protected]>: Temporary lookup failure; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<mx2.slc.paypal.com>

Postfix is startet right, now errors shown during startup:
netstat -tnlp:
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 2145/master
tcp 0 0 0.0.0.0:587 0.0.0.0:* LISTEN 2145/master

ISPconfig is located on an Strato vServer, 10 Days before my mysql database crashes, but I think the databases were repaired correctly. Every database works, even ispconfig.

This failure is also reported in the mail.info:

Jun 28 10:32:22 h2101310 postfix/smtp[3640]: A15895A48344: to=<[email protected]>, orig_to=<root>, relay=127.0.0.1[127.0.0.1]:10024, delay=107043, delays=107038/4.7/0.02/0.54, dsn=4.3.0, status=deferred (host 127.0.0.1[127.0.0.1] said: 451 4.3.0 id=02304-09 - Temporary MTA failure on relaying, from MTA([127.0.0.1]:10025): 451 4.3.0 Error: queue file write error (in reply to end of DATA command))

Any ideas? I don't want to reinstall the hole server...