[Exim] filters

Is It possible to access a database within a filter.. I would like to
lookup the senders address something like this

# Exim filter
#if ${lookup mysql select sender where user='${quote_mysql:$local_part}'
and sender='${quote_mysql:$sender_address}'} is $sender_address
#then
# mail to $sender_address
# mail text exists in database
#else
# mail to $sender_address
# mail text DOSEN't exists in database
#endif



am I barking up the wrong tree? will I have to use and external app to
do this?