trouble deleting emails

I have a simple script here. It is suppost to delete an email if the body of the email is “itunes”. it works fine, but it will delete the email if it has any word or anything with “itunes” in it. So, it will delete a message if is has something like “youlikeITUNES” or “Do you like iTunes?” in it. So, I tried to use the second script. It runs fine, but does nothing. Does anyone know how I can tell it to delete the message if the content is ONLY “itunes”?

tell application "Mail"
	delete (first message of inbox whose content contains "itunes")
end tell
tell application "Mail"
	delete (first message of inbox whose content is "itunes")
end tell

This works

delete (first message of inbox whose first word of content is "itunes")