[Exim] whole redirect fails if single recipient fails

Hello,

I've created an alias-router with the redirect-transport. When I enter
multiple recipients for one alias, the incoming is forwarded to all
recipients. But in longer lists it may happen, that only one address is
not correct, possibly causing a loop on this server, so that the
incoming email is bounced. How can I disable this?
Another example: An feature allow_fail does exist. Some users want to
receive mail on a certain address but want the sender to be in the
believe, that the mail couldn't be delivered. So I would insert an alias
with one recipient and the :fail:-item. Unfortunatly also in this cause,
the whole incoming mail gets bounced, so it will never be delivered to
the recipient.

Regards
Marten