This option has to be physically turned on by the sender, it is not an
automatic thing, so If you never turned it on, then you don’t have to worry!
For those who have it switched on (either by choice or somebody else did it
for you) for Outlook express (I assume the same for outlook) Go to:
and click the highlighted box to remove the arrow. If the box is not ticked
when you get there, then you are not requesting receipts and can just exit
that part back to your desktop. If you have Windows XP there is a box in the
same window allowing you to refuse all receipt requests automatically .