[exim] Exim Filter

I have this basically in one of my filter files:

nano nano /etc/virtual/domainname.com/filter

if
    $h_X-Spam-Status: contains "Yes,"
then
    if
        $local_part is "username"
    then

        save /home/username/Maildir/.INBOX.spam/new/ 660
    else
        save /home/username/imap/$domain/$local_part/Maildir/.INBOX.spam/new/
660

    endif
    finish
endif

What it does is if a message is scored as SPAM it goes to the users
SPAM folder. Weird thing is that messages scored as spam going to
spam folder do not have the date appended to the front of the file
name like the messages that do not score as spam do that arrive in the
users regular folder.

Can anyone tell me how I can resolve that? I want the date appended
to the front of the file name to help with some utillities I want to
run on the files. Daily report of any new messages in SPAM folder.
Deleting messages in spam folder over 30 days old and etc.

Matt