Removing BCC with Apple Script when automatically BCC myself is set in pref

Question

I have "Automatically Bcc myself" set in the Mail Composing preferences, which I like because I get a copy of email that I send. I also have an apple script that forwards messages to an email address. When I used this apple script on Tiger, the BCC option was never added (it might have been a bug with Mail in Tiger); however, now on Leopard, the BCC option is always added when I used the apple script.
I've tried setting the BCC field to Null and Blank, but that doesn't seem to work. I suspect that the field is set upon send or the "make new" directive. Does anyone know a way to tell Mail to not Bcc automatically in an Apple Script?
Here is the forward apple script program:
(* Cf. http://www.macosxhints.com/article.php?story=20060219014940761 *)
(* RS 31st July 2006 *)
set theAuthority to "person AT here"
tell application "Mail"
set theMessages to the selection
repeat with thisMessage in theMessages
set newMessage to make new outgoing message at end of outgoing messages
tell newMessage
set visible to true (* comment out whole line to stop 'blinking' windows *)
set content to thisMessage's source
set subject to "Fwd: " & thisMessage's subject
set bcc to null (* my attempt to set bcc to null or blank *)
make new to recipient with properties {address:theAuthority}
end tell
send newMessage
set read status of thisMessage to true
set was forwarded of thisMessage to true
set junk mail status of thisMessage to true
end repeat
end tell

Answer 1

Thanks for that reply!
After more google searching, I found this on http://www.macosxhints.com/article.php?story=20040425063255443
One of the responses said that you can add the lines:
delete bcc recipients
delete cc recipients
"in that order" to the new message tell and get rid of the recipients. I had tried the delete before, but I thought I had to get the recipients before I deleted them. I'm not a very good apple script person. Here is my final script
(* Cf. http://www.macosxhints.com/article.php?story=20060219014940761 *)
(* RS 31st July 2006 *)
set theAuthority to "email address here"
(* or your personal Knujon address *)
tell application "Mail"
set theMessages to the selection
repeat with thisMessage in theMessages
set newMessage to make new outgoing message at end of outgoing messages
tell newMessage
set visible to false (* comment out whole line to stop 'blinking' windows *)
set content to thisMessage's source
set subject to "Fwd: " & thisMessage's subject
make new to recipient with properties {address:theAuthority}
delete bcc recipients
delete cc recipients
end tell
send newMessage
set read status of thisMessage to true
set was forwarded of thisMessage to true
set junk mail status of thisMessage to true
end repeat
end tell