script side effect?

(Sorry if this is an obvious thing I’m missing)

I have an applescript that redirects the currently selected message in Mail (4.5), then deletes the message.

The redirect is from one IMAP account (address 1) to another (address 2), both Gmail accts.

The problem is that I’m getting the original message plunked back in address 1’s inbox (with the redirect icon).
I don’t want this (hence having my applescript delete the message)…
…is this occurring because of something related to IMAP?
…or a conflict between Gmail and, and how they handle redirected mail?
…or something beyond my grasp?

the code:

tell application "Mail"
	set theSelectedMessages to selection
	set reroutedmsg to item 1 of theSelectedMessages
	set theOutgoingMessage to redirect reroutedmsg without opening window
	make new to recipient at end of to recipients of theOutgoingMessage with properties {address:""}
	send theOutgoingMessage
	delete theSelectedMessages
end tell