File Format error

hey,

I use FreeBSD 2.2.5 with sh shell, when I try define .procmailrc that
explained in procmailex manual page, I get the bad file format like this:

yustanto(_at_)students(_dot_)itb(_dot_)ac(_dot_)id^@^@

in vacation.cache file.

This is procmailex sample for above file output:

         # Perform a quick check to see if the mail was addressed to us

             * $^To:.*\<$\LOGNAME\>
              # Don't reply to daemons and mailinglists
             * !^FROM_DAEMON
              # Mail loops are evil
             * !^X-Loop: your(_at_)own(_dot_)mail(_dot_)address
             | formail -rD 8192 vacation.cache

               :0 ehc         # if the name was not in the cache
               | (formail -rA"Precedence: junk" \
                    -A"X-Loop: your(_at_)own(_dot_)mail(_dot_)address" ; \
                  echo "I received your mail,"; \
                  echo "but I won't be back until Monday."; \
                  echo "-- "; cat $HOME/.signature \
                 ) | $SENDMAIL -oi -t 



My questions :
        1. How to make the output file without ^(_at_)^@ code.
        2. If I want to add other characters if new address was not in the
cache, like this:
        adnan(_at_)seroja(_dot_)com,\
        elvi(_at_)sentrika(_dot_)co(_dot_)id,\
        "sorba Majala" <sorba(_at_)lovia(_dot_)org>


        what must i add into my .procmailrc ??

        3. How to remove one mail address from that cache ? (like
unsubscribe) in mailinglist.


Thank.

sincerely,

Yustanto