gmail mail sent from OE appears in gmail folder

I set up a gmail account a couple of years ago (as a precaution when it looked like tiscali might die a sudden death). I've never really used it, but I've just tried sending a few emails and noticed that emails I send (using the gmail account) from Outlook Express then immediately appear in the Sent folder of the gmail webmail.

Not only is this not what I want (as I have a copy in my OE Sent items), I find it rather odd given that gmail has a setting that removes received (Inbox) items from gmail webmail once they have been accessed with POP (e.g. downloaded to OE), so begs the question as to why gmail wants to keep copies of sent items.

Or is there some setting in gmail that I haven't been able to locate?