[ic] Supress mail receipts

[Interchange User]

I'd like to know how I can suppress sending of mail receipts to both 
customer and admin at Checkout page, and only send them at Receipt 
page (ie, after an external payment gateway).  

I was thinking of writing a perl script to format an email nicely 
after Checkout page, save it into a file with the order number as 
filename, then at Receipt page, just email that file (and delete it, 
of course).  However, I understand IC's safe mode doesn't allow for 
creation of files just like that (?)  Is there a way I can do that?  
Or any simpler suggestions to achieving my goal of only sending email 
at Receipt page?

My order procedure is:
Checkout page -> WorldPay payment page -> Receipt page

At my Checkout page, I saved all order info into the database first.
At my Receipt page, I retrieved these info to display online.

In order to allow Checkout page to save info into database, I did 
this:

<INPUT TYPE=hidden NAME=mv_order_profile VALUE=my_checkout_profile>
<INPUT TYPE=hidden NAME=mv_order_receipt VALUE="ord/wp_redirect">

where 
wp_redirect is used to format the parameters nicely before sending to 
WorldPay, and my_checkout_profile has a &final=yes.

However, this approach will send the mail receipts to customer and 
admin, even before the payment is made.  Setting:

<INPUT TYPE=hidden NAME=mv_order_route   
VALUE="[either]__ORDER_ROUTES__[or]log[/either]">
and
ORDER_ROUTES    log     Order

didn't work either.  I combed the archives, saw a few similar 
queries, but no proper solution.  Really didn't want to go the way of 
sending email to /dev/null, and looks like setting 
Route main empty 1
didn't work too (someone tried).

Much thanks for any tips!