[Dovecot] failing to deliver to one of multiple destinations

[Edgar Fuß]

> No, when delivery fails entirely, the deliver binary should give an  
> appropriate exit code, indicating that the MTA needs to try again later  
> or bounce the message.
OK, I would have expected that.

> What do the Dovecot and MTA logs say?  
I will send you that information in private mail.

> Furthermore, the output of dovecot -n would help us find and solve the  
> issue. And finally, your Sieve script may also be relevant.
See above.

Thanks for your help.