[Exim] Permitting relaying on rcpt to

Dear folks,

I am sorry if this is a dumb question that might
be answered by the docs but I need a quick solution for this.

Is there any config-variable that can be used for allowing
relaying to a specific recipient determined in the SMTP-Session?
Like recipient_allow_relay = test@???

Thanks for any hint!

Regards,
Sascha

---
Sascha E. Pollok
Network Operations / Internet Port Hamburg
Grosse Reichenstrasse 27
D-20457 Hamburg
Germany
Tel. +49 40 37 49 19-0
Fax +49 40 37 49 19-29
Email sp@???