I mentioned that....... click at the contact > right side, the address will appear.
In case you did not know what I meant :
Go to people window
Open outlook.com > top left next to the logo Outlook, there is a down arrow > if you don't see the arrow, place your cursor over the logo Outlook, a down arrow will appear > click the arrow > click People.
In the people, all your contacts are on the left.
If you click at a contact, the address will appear on the right side. Yes ?
In order words, each contact has an address.
If you can confirm that, then there is no problem sending e-amil. Yes ?