Unofficial general is acting unofficially.
If you click on an enemy sector in the zoom view, a box will pop up in the lower right with the owners name. That name is a hyperlink to their profile page (opens in another window) that will let you send them a note.
In terms of notes, you can do whatever you both agree on, but the system will still treat you as enemies, including flyover attacking of air units.
There's also no 'protection' if one of you violates the agreement.
