External Sharing

I've been reading up on external sharing recently. If you have a lot of external sharing going on, have a look at Azure B2B Collaboration which allows you to manage it in a more controlled way using AAD.

Here's the recent Ignite demo and slidedeck

https://techcommunity.microsoft.com/t5/Microsoft-Ignite-Content/BRK3108-Share-corporate-resources-with-your-partners-using-Azure/m-p/10588/highlight/true#M582

Another short video

https://techcommunity.microsoft.com/t5/Azure-Active-Directory/How-to-simplify-external-resource-sharing-with-Azure-AD-B2B/m-p/12363/highlight/true#M4

Learn all about the Azure AD B2B Collaboration Preview

https://blogs.technet.microsoft.com/enterprisemobility/2015/09/15/learn-all-about-the-azure-ad-b2b-collaboration-preview/

Here's another guide to sharing with SP Online using AAD

http://blog.ciaops.com/2015/11/using-azure-ad-b2b-sharing-with.html