I thought delaying it (as you said) works? My colleague did it and it showed the delayed time, not the actual send time.
I believe this to be true, however, your system has to be in Outlook at the time. There's a different way to schedule the delivery time, but as said above, the time the E-Mail is sent is still visible, and this is because (technically) the E-Mail has been sent, but is being held by the E-Mail Server until the time requested to deliver. The delayed send feature works by leaving the E-Mail in your Outbox until the time to send it. I've done this before - once WITHOUT the system being on - and I did not receive the E-Mail until the system was on. This means, the E-Mail was in my local Outbox - not in the E-Mail Server - and thus, would not be received until my system was on and in Outlook. When I retried, I left my system on and Outlook loaded, and had the delayed email send me a notice at 1:00 a.m., which I received promptly at 1:00 a.m. on my synchronized BlackBerry. The date and time showed exactly what I wanted.
Now - at the time I tested this, I believe I was still using Outlook 2003. The above information might have changed.