[Exim] Filter boggle (3.35)

if ("${lookup{$reply_address:}lsearch{$home/blacklist.senders}{$value}}" is
"trash")
then
seen save /dev/null/
endif

[gefu@waldorf gefu]$ cat blacklist.senders
spamfilter2@???: trash
[gefu@waldorf gefu]$


Why doesnt this rule do anything? If i send a mail from the
spamfilter2@??? addy, it gets processed by the local_delivery director?