Microsoft will be releasing what’s called ‘Outlook.com Premium’ – a paid upgrade to the free Outlook.com mail hosting but also free to Office 365 ‘subscribers’.
Serial Microsoft leaker ‘Walking Cat’ published a shot of the pilot for Outlook.com Premium which gives a peek into what we can expect.

Personalized Addresses – you’ll be able to link your own domain name to an Outlook.com account. This will be done via GoDaddy.com. If you have the freddagg.com domain you’ll be able to link, say, Bruce@freddagg.com and use it with Outlook.com to send/receive messages with that address. It’s not known yet if the link is for individual addresses or the entire domain has to be linked to Outlook.com. There’s a link from Outlook.com Premium to buy a domain via goDaddy but no indication, yet, for existing GoDaddy customers.
Sharing – Sharing calendars, contacts and documents will be possible. There’s a mention of automatic ‘relationships between people who have email addresses on your domain’ which suggests that the personalized email address service is on a ‘whole domain’ basis.
Ad-free – the browser based version of Outlook.com will be advertisement free for Premium customers. Of course, Outlook.com can already be synced with Outlook for Windows/Mac so this isn’t as important for Office 365 customers.
Powered by Outlook.com – all the hype aside, the best news about Outlook.com is the seamless links with Outlook desktop software. Gone are the add-ons, Outlook.com syncs with Outlook software the same way that Exchange Server does; with Microsoft’s ActiveSync. That makes is easy to sync Outlook.com with Outlook desktop software plus Apple, Android and Windows devices.
All up, Outlook.com Premium should be of interest to existing Office 365 subscribers. Being able to use your own domain for email addresses is possible now, but the link to GoDaddy should make it a lot easier to manage.