After several months of "by invitation only", the premium custom domain service for outlook.com is now open to US residents. (No word yet on when it will be available in other countries). While the regular price is $49.99/year, it's currently available at a special price of $19.95/year now through Dec 31st 2016.
What do you get for that price? For starters, a custom domain name and up to 5 addresses to share with family and friends. If you already own a domain name, you can move it to Outlook.com or get a new domain name from Microsoft (free for the first year, $10/year after that.)
When the addresses are set up, calendars, contacts, and documents are automatically configured to share between the mailboxes.
As a bonus, it's the ad-free version of Outlook.com.
For more information or to sign up, visit https://premium.outlook.com. You'll need to log in with your existing Microsoft Account or create a new Microsoft Account.