[Exim] autoreply defer

Hello,

I'm using an autoreply transport, where the file-location is looked up
dynamically using lsearch. If the file isn't available, the
reply-message is deferred:

2004-06-08 17:45:29 1BXin3-0007ht-45 == lehmann3@???
R=autoreply_addresses T=address_autoreply defer (0): Failed to open file
/vrmd/exim-4.32/replytext when sending message from address_autoreply
transport: No such file or directory

How can I tell exim not to defer (and retry later) but just skip the
transport, if the file is not available?

I also tried with the text-option and ${readfile...}, but if the
expansion fails, an error message is sent to the sender and I don't want
this, too.

Regards
Marten