[exim] router yields tainted data

Hi,

I have here a router which yields tainted data and I don‘t understand why - especially since it works on some machines and not on others:

Log-output:

exim -v -bt test@???

LOG: MAIN PANIC
Tainted filename '/usr/local/etc/exim/redirects/domain.com'
test@??? cannot be resolved at this time: dynamic_reroute router: failed to expand "${readfile{/usr/local/etc/exim/redirects/$domain}{}}": failed to open /usr/local/etc/exim/redirects/domain.com: Permission denied (euid=0 egid=9025)

dynamic_reroute:
    driver = manualroute
    transport = remote_smtp
    domains = dsearch,ret=key;/usr/local/etc/exim/redirects
    route_list = * ${readfile{/usr/local/etc/exim/redirects/$domain_data}{}}

in the directory /use/local/etc/exit/redirects are files that look like „domain.com“ and contain just an ip-address.

Why is the data tainted? I use a dsearch with a return-value and $domain_data for the route_list. So it should be de-tainted, shouldn‘t it?

Best,

Niels