Autoresponder question

I use the following autoresponder when I'm away. This one implements an ACK  
once. But I would like that people get max one ACK per week.

How can I do that?

:0 Whc: vacation.lock
* !^FROM_DAEMON
* !^X-Loop: G(_dot_)C(_dot_)Th(_dot_)Wierda(_at_)AWT(_dot_)nl
| formail -rD 8192 vacation.cache
    :0 ehc         # if the name was not in the cache
    | (formail -rA"Precedence: junk" \
       -A"X-Loop: G(_dot_)C(_dot_)Th(_dot_)Wierda(_at_)AWT(_dot_)nl" ; \
      echo "I received your mail, but I won't be able to reply soon. "; \
       echo "Contact Secretariat(_at_)AWT(_dot_)nl if it is urgent."; \
       echo ""; \
       echo "Yours,"; \
       echo ""; \
       echo "Ik heb uw bericht ontvangen ,maar ik ben niet in staat snel "; \
       echo "te reageren. "; \
       echo "In dringende gevallen kunt u kontakt opnemen met "; \
       echo "Secretariaat(_at_)AWT(_dot_)nl(_dot_)"; \
       echo ""; \
       echo "Hoogachtend,"; \
       echo ""; \
       echo "-- "; cat $HOME/.signature \
      ) | $SENDMAIL -oi -t

Thanks,

--
Gerben Wierda,

Stafmedewerker Adviesraad voor het Wetenschaps- en Technologiebeleid.
Staff member Advisory Council for Science and Technology Policy
Javastraat 42, 2585 AP, 's-Gravenhage, The Hague, The Netherlands
Tel (+31) 70 3639922    Fax (+31) 70 3608992
http://www.AWT.nl/

"One foolish wise man can state more
        than a thousand wise fools can question."
"Doubters need to understand believes.
        Believers need not understand doubt."