Using Office 365 in an Extranet Scenario

This is something that has been one of the most exciting aspects of Office 365 for me. The fast and effective way of creating an Extranet scenario without the need to worry about firewalls, external user accounts or certificates.
When you sign up with Office 365 on an Enterprise plan you get access to your SharePoint Admin control panel. (Sorry folks, the Small business version aka Professional Plan does not have this feature)
There you can create several site collections and even allow external user which have not been set up in your AD or on Office 365 to access your SharePoint sites.
This is great news for companies who work closely with clients and want to use the SharePoint Online part of Office 365 as a information sharing hub.
When you open your first SharePoint team site at :https://youcompanyname.sharepoint.com" as administrator you will notice a new Site Action menu item called "Share Site". This is where you can add users as Visitor or Member to your site or sub site. You will also notice that this does not seem to work for external users straight away. You first need to change two settings for externals to gain access.

1. On the SharePoint Administration page accessible via https://portal.microsoftonline.com/admin/default.aspx you will find a button that says Settings. Use this button to enable external access for your whole account. 
2. Then go to the Site Settings of your private site collection via the Site Actions menu and activate the External User Invitations feature under Site Collection Features.

That's it folks. From now on you can add any email address to the Share Site dialog and that person will receive an invitation email to connect to your SharePoint site.
Using what username and password you might ask? Windows Live ID solves this problem for us. This part of Office 365 integrates via federation with Windows Live ID and so the external user can either use their existing Windows Live ID or sign up for a new one.
Once the user has signed in with their Live ID, they will appear in the group that you have added them to. Not any sooner though. They will also appear with their Live ID email which might be different from the email address you sent the invitation to. So before you get a heart attack thinking you got hacked by some random person, double check the email if it does not belong to someone you know who favours cryptic email addresses.

Happy Sharing!