Just back from vacation. Sorry for the late reply, hope it helps..

If he can't or won't put it in a proper content filter then I noticed this snippet:

--- mailbox_command = /usr/local/bin/maildrop ${revipient}

---

Should be:

mailbox_command = /usr/local/bin/maildrop -d ${recipient}

Note the "-d" and the correct spelling of "recipient"

Also, in maildroprc there's "spamc -u spamd". maildrop will switch to the user being delivered to so ensure that all users are able to read spamd's spamassassin config file.