Office 365 has been a great way to communicate and access shared content with others inside your company. However, the ability to collaborate with others outside of your organization using Office 365 has remained a commonly requested feature by users.
Microsoft is addressing this gap with a new feature called "guest access" which will enable people outside of your company to be included in an Office 365 group. This will permit nominated guests to access content stored in SharePoint Online, including OneNote notebooks, while also receiving email, calendar invites and cloud-based attachments sent to the group.
Guest access will work with any email accounts associated corporate or consumer domain. Guest identifies linked to an existing Microsoft account, such as Office 365 or Outlook.com accounts, will simply sign in with their existing credentials to gain access. Otherwise, invited guests will be prompted to create a Microsoft account before being able to proceed further.
However, as with any form of access control, group owners should double check the group"s assigned access to document libraries to prevent invited users from being able to view and download company confidential content.
The feature has already begun its progressive roll out but will require the enablement of SharePoint external sharing at the organizational level. More information about guess access for Office 365 Groups will be made available later this month at Microsoft Ignite.
Source: Office Blog