[till]

Before you emptied the mailqueue, had there been many messages in the queue?

I'am asking because this looks like you have som spam problems trough a web form:

May 31 20:07:39 fingers postfix/qmgr[20260]: 03ED8B3C094: from=<www-data@fingers.hu>, size=2305, nrcpt=1 (queue active)
May 31 20:07:39 fingers postfix/qmgr[20260]: 0869BB3C127: from=<www-data@fingers.hu>, size=2307, nrcpt=1 (queue active)
May 31 20:07:39 fingers postfix/qmgr[20260]: E65C5B3C120: from=<www-data@fingers.hu>, size=2310, nrcpt=1 (queue active)
May 31 20:07:39 fingers postfix/qmgr[20260]: E7F35B3C145: from=<www-data@fingers.hu>, size=2311, nrcpt=1 (queue active)
May 31 20:07:39 fingers postfix/qmgr[20260]: EEFCFB3C12C: from=<www-data@fingers.hu>, size=2312, nrcpt=1 (queue active)
May 31 20:07:39 fingers postfix/qmgr[20260]: E4368B3C139: from=<www-data@fingers.hu>, size=2310, nrcpt=1 (queue active)