Exchange shouldn't send the mail until the user hits send in outlook.
Verify the email in sent items with one received - may be a user issue? If
the email was indeed truncated check the anti-spam measures at both ends and
the size limits if it was a large email. You could also track the email in
the exchange administrator message tracking center.
As far as resending NDR's on boot, it is probably not related to this issue
but related to this greylisting issue:
> On Monday, I had a client (Outlook 2003 attached to SBS2003r2
> exchange) who sent a few emails that where cut off half way through.
> He received replies from the recipients saying, you sent the email
> before you finished. I rebooted the server and when it restarted,
> several users received NDR's from emails that they had sent a week
> earlier. I assume that these NDR's were fromemails stuck in the
> exchange STMP queue, which I failed to check before rebooting, but I
> am not sure.
> Anyone know why an email might get cut off? What would you recommend
> as preventative maintenance at this point? Please advise.