[courier-users] Error: No multi-recipient error messages, please - access denied ?

[Knallfrosch <kna...@my...>]

Hello Everyone

I have a maillist for my friends configured with an alias in my courier config.
Three receivers have their mailbox at GMX.ch. This receiver-smtp 
(mx0.gmx.net) rejects the mail(s) to them every time.
All other servers / receiver accept mail without error. There is also 
another server where two persons have their boxes and it works.

Log:

Dec  4 20:32:00 pluto courieresmtp: 
id=00004756.3DEE5829.00007386,from=<sender@???.ch>,addr=<rec...@gm...>: 
550 {mx0
24-rz3} No multi-recipient error messages, please - access denied
Dec  4 20:32:00 pluto courieresmtp: 
id=00004756.3DEE5829.00007386,from=<sender@???.ch>,addr=<rec...@gm...>: 
550 {mx024-rz3} No mult
i-recipient error messages, please - access denied
Dec  4 20:32:00 pluto courieresmtp: 
id=00004756.3DEE5829.00007386,from=<sender@???.ch>,addr=<rec...@gm...>: 
550 {mx024-rz3} No multi
-recipient error messages, please - access denied
Dec  4 20:32:00 pluto courieresmtp: 
id=00004756.3DEE5829.00007386,from=<sender@???.ch>,addr=<rec...@gm...>,status: 
f
ailure

sender / receiver names replaced :)

I think my couriermta tries to send all three mails together. Which is a 
good idea at first glace.
I've tried to find the courier config switch to split the mails and send 
them individually. But I can't find it :(


Can anyone help me?

thanx
Christian