Email received and editable (Outlook 2013 with Exchange 2013).

Hello there,

I have noticed a strange Outlook 2013 behavior (or maybe this is a new feature I'm not aware of :) ). Sometimes I find an email in my inbox which was sent to me, however it is open for edit. I can see FROM filed greyed out, but TO, CC and the email subject and body can be edited! I can click SEND and it goes out. How come this is happening with an email I received form someone?

Note: this kind of message has a specific icon related:

Any idea what is this?

Thanks,

Mariusz

Mario