While setting up Outlook to deliver mail to different inboxes is a bit cumbersome, you can sort the Inbox by account (and then by date, for example) easily. It's not ideal, but at least all messages that belong together are together.
Sort Your Outlook Inbox by Email Account
To sort the emails in your Outlook Inbox by the account through which they were received:
- Select View | Current View | Customize Current View... or View | Arrange By | Current View | Customize Current View... from the menu.
- Click the Sort button.
- Make sure All Mail Fields is selected under Select available fields from: at the bottom of the dialog that comes up.
- Now choose E-mail Account from the Sort items by drop-down menu.
- Optionally, select criteria for further sorting using the Then by fields.
- Click OK.
- Click OK again.