[exim] requeue message when address_pipe transport fails?

Hello everyone,

I'm running request-tracker on a system with exim4.

When exim4 fails to pipe a message to the rt message handler, the
message gets bounced:

2009-02-14 10:21:59 1LYGik-0002vi-Io ** |/usr/bin/rt-mailgate --queue xxxxxx --url http://xxxxx/rt/ --action correspond <xxxx@xxxx> R=system_aliases T=address_pipe: Child process of address_pipe transport returned 75 (could mean temporary error) from command: /usr/bin/rt-mailgate
2009-02-14 10:21:59 1LYGil-0002vn-HN <= <> R=1LYGik-0002vi-Io U=Debian-exim P=local S=5154 T="Mail delivery failed: returning message to sender"



Is there a configuration option which causes exim to requeue the message
instead of bouncing it back instantly?