As discribed here:
... agents should be able to forward messages directed at their personal adresses to the support address while preserving the original sender's address.
In this discussion is stated that it isn't working when using Outlook, because Outlook supposedly is stripping the originating mailaddress form the headers.
Outlook isn't, it preserves the originating mailaddress. I could send you some screenshots, but will not post them here for privacy reasons.
I would like very much this feature to work, because users will keep sending to agent's addresses, how many times you ask them not to (as do others, because this question is popping up every once and a while in the forums).
By my own experience, this feature is a working feature within Zendesk, so technically it should be possible.