Distribution lists help you easily send emails to a larger group of people without having to add individual email addresses. Set groups of friends and colleagues or create an email list that will mail to every email that you have.

To set up a mailing list in Outlook:

To begin select File -> New -> Distribution List
Type the desired name of your new list under Name (Such as Sales Team, New Project Team, or Friends)
You can add new members to the list immediately with the Add New… and Select Members… buttons.
Click Save and Close.
Now, when you add new recipients to your email list you will be able to choose your new distribution list rather than all the individuals that it contains.