Now that I have tried to contact you, I can only bow before
Wouter's wisdom:
orange.net platform: said: 552 5.2.2 Over quota (in reply to RCPT TO command)
The failing address was postmaster, BTW. ;-)
Update:
While talking to 193.252.23.4:
Recipient: <abuse@orange.net>
Reason: 550 <abuse@orange.net>: Recipient address rejected: User unknown