1. Do you mean the SharePoint Online service included in your Office 365 E plan by saying “Office 365 Enterprise SharePoint hosted” and “the hosted SharePoint”?
A: External users, when reaching the login.microsoft.com and entering AD creds are not redirected to the hosted
SharePoint. Which if you use Fiddler can see what I am speaking of.
2. Does the issue occur to all the external users? If the external users use Microsoft accounts (like Hotmail, SkyDrive or Xbox LIVE), can they encounter this issue?
A: Yes, all external users who are federated or hold their sign in creds in our AD. No, this would/does not happen if they used a (Hotmail, SkyDrive or Xbox Live account, since those are Microsoft or cloud managed accounts.
Thanks, Jerry!