The problem is pretty simple and yet hard to understand.
Outlook 2013 uses the Exchange ActiveSync (EAS) as a protocol when accessing the server "m.hotmail.com". This is not a fully qualified Exchange access but only a limited one. The EAS has been developed for mobile devices and therefore has some limitations.
The Outlook Hotmail Connector used not the EAS 14.0 but a slightly different approch. This had advantages, but also disadvantages.
Unfortunately with Outlook 2013 the access to Hotmail (Live etc.) is only possible with the EAS and not the Outlook Hotmail Connector any more.
As a result we have to face some of these limitations:
1. No import of external data into a store (not via .PST or .CSV)
2. No moving of items (as this is considered as "import")
3. No chance to use the Hotmail datastore as a folder for POP3 mailboxes (as this is considered as "import")
4. Inabillity to use a different mail address (even it is allowed in the Hotmail web frontend or fetched by hotmail) for sending
As a workaround use Outlook 2007 or 2010 with the Outlook Hotmail Connector (as mentioned in the article "Cannot move the items" error when you move items from an Outlook 2013 client to an EAS store
- nice joke!) or create an extra PST-file. Use this PST-File for your POP3 accounts.
Bad thing: you have two different stores and cannot sync them as you were able before.
Microsoft has to fix this - best option would be to switch from EAS to the full Exchange protocol for all Hotmail (and Live) mailboxes. But I think - this is utopic as Microsoft wants to have paying customers for the Exchange 365.