Setting a "Reply To" address

Question

I scripted Mail to create a new message and enter all the info I want EXCEPT I can't figure out how to get it to enter the REPLY TO address. Can anyone help me?
Here is my "test" script:
tell application "Mail"
activate
set theReplyToAddress to "<[email protected]>"
set theMessage to "This is text for the body of the message."
set theSubject to "This is the Subject"
set theSendingAccount to "Me <[email protected]>"
set theRecipient to "<[email protected]>"
set newMessage to (make new outgoing message with properties {visible:true, subject:theSubject, sender:theSendingAccount, content:theMessage})
tell newMessage
make new to recipient with properties {address:theRecipient}
set reply to to theReplyToAddress -- -- -- --> can't figure this out
end tell
end tell

Answer 1

I meant the field that is literally labeled "Reply To" rather than the sending "Account" name...
The field has to first be set to display in Mail, then it appears directly above the "Subject" field in an outgoing message. It's an alternative to "reply to." I need it because I want my regular "From" address to still appear (for recognition), but I don't want the recipient to be able to automatically reply to that address when they hit REPLY. I want them to instead reply to an address that will send them an auto response with special instructions. This is how I use "Reply To" -- on the few occasions I do use it.
I was very anxious to get a reply on this so I posted a similar question at another Applescripting site. On that forum, two posters said the "Reply To" field in an outgoing message cannot be set (as a property). So I was hoping there might be another way to accomplish it, like by setting the clipboard with the "reply to" address and having Applescript paste it into the "Reply To" field. But I haven't the slightest idea how to do -- if it's even possible.
Would you have any suggestions?
Thank you.