[exim] errors_to must point to the caller's address

Hello,

I have a filter specification

elif $h_from: contains "rd@???" then save 
Maildir/.Telekommunikation.klarmobil/
                                                    deliver 
rdorsch@??? errors_to rd@???

which works well.

When I replace the errors_to with rd@??? exim does not deliver and
sends me an email with

The userforward router encountered the following error(s):

errors_to must point to the caller's address

No valid addresses were generated.


I am wondering why only the dyndns entry hostname of the server works but not
its regular DNS entry which is also set with hostname.

rd@bokomoko:/etc/exim4$ hostname
bokomoko.de
rd@bokomoko:/etc/exim4$

How does exim4 calculate the caller's address?

Many thanks,
Rainer

--
Rainer Dorsch
Lärchenstr. 6
D-72135 Dettenhausen
07157-734133
email: rdorsch@???
jabber: rdorsch@???
GPG Fingerprint: 5966 C54C 2B3C 42CC 1F4F 8F59 E3A8 C538 7519 141E
Full GPG key: http://pgp.mit.edu/