To create a new synchronized contact, do the following:
- Create a new contact from scratch.
- Open up contact properties, select the Office 365 tab, configure the Alias, and click Apply.
- Click Mail Enable and select Yes or No to create email addresses for all verified domains.
- Click Proxy Addresses, enter the external email address of the contact, configure it as the primary SMTP address, and click OK.
- Select Synchronize AD with Office 365 and click OK.