yeap... blame the hardware.
There are a number of logical scenarios that
could result in accidental deletion so I wouldn't take it personally. You
could just resend and not mention the receipt - just say you hadn't gotten a
reply and are resending in case it got lost. Do pay attention to the subject
line - it could be something he thought was spam, especially if he didn't
recognize your name. For that matter - outlook mighta junk mailed it and he
never saw it.