Deleting computer memory
When I start to type an e-mail address my Outlook e-mail "To" line presents me with many options of addresses starting with the same two initial characters, for instance when I e-mail friend Peter XXX I get about 8 addresses for people called Peter that I have e-mailed in the past, it makes no difference that I may have deleted some from my Contacts list, it seems that my computer memory provides all these options ?
Unfortunately, for one friend called Peter, the first option shown is an address that he no longer uses, and unless I'm quick to spot it, that is the address that gets selected.
How do I delete all the e-mail addresses that I no longer require from the computer memory ?
Worse ... said Peter e-mailed me today and instead of his "To" line showing my e-mail address, it showed my Microsoft account username and ..... my Microsoft Password ! That's scary. How did his computer know my Microsoft account details when he typed me address ?