When I want to send an email to some people, I start to enter their name and their email addresses pop up for me to choose one. I cannot seem to be able to delete old addresses. Anyone know how?
I may be wrong but what Master Muse may be referring to is that Outlook actually memorizes addresses that you type in the 'To' field, even if they're not in your address book. So, next time you go to type in an address, it automatically tries to complete the address for you based on the ones you have typed before, not just the ones in your address book.
Example: You send an email to happyhooker@fuckme.com but you don't add her to your address book because you don't really want that address in there permanently. Later, you start to type harryballs@hairclubformen.com while your boss is standing at your side. As soon as you type the first 2 letters, Outlook automatically shows the happyhooker address and boss now owns your ass.