But if I shared a file (and made it editable) to an external user, if they have no Microsoft Account, they can't edit it online I correct? I thought MS stated last month that you could share with external users and they did not need a login. It would send a "code" to their email and that's all they needed. I suppose they would need Word, etc. online to make use of this though right?
From MS below:
If your OneDrive and SharePoint Online external sharing settings are set to allow sharing with new external users, new external users (that have a file or folder securely shared with them) will be able to access the content without needing an Office 365 account or a Microsoft account. Instead, recipients who are outside of your organization will be sent an email message with a time-limited, single-use verification code when they access the file or folder. By entering the verification code, the user proves ownership of the email account to which the secure link was sent. Securely sharing a file or folder is the process of sharing in a way where recipients must prove that they're intended recipients that the original sharer specified. End-users can do this in the same way that they already do. (by changing the link settings to only work for specific people in the Share dialog) We're also introducing a new admin control which will allow you to specify how often external recipients must re-verify their email address and enter a new code. This protects your organization from cases where an external recipient’s employment status changes.