This guide will show you how to add an extra email address to an existing email account.
NOTE: This is called an email alias.
1. First make sure that your account is an Administator account (see: FAQ #81269).
2. Log in to Microsoft Online Portal with you administrator account.
3. Click users and groups.
4. Click check box for the account you want to add the alias for. Click Edit mailbox permissions.
5. Click email address.
6. Click the plus sign (+).
7. Enter in the email alias you want to add.
NOTE: By checking the option Make this the reply address the new alias will be the address displayed when you are sending emails.
7. Click Ok.
8. Click Save.
You have now added a new email alias in Office 365.
NOTE: You can test it by sending an email to it.
In this case the mail would go to firstname.lastname@example.org.