When I send a photo by email using "Mail" it appears with a watermark "For Review Only". I'm probably missing something obvious here, but does anyone know how turn this off please? This is pretty irritating as I'm sure I never turned it on in the first place!
Is it possible you have this set as a watermark in the export preset assigned to emailing?
"Aperture→Presets→Image Export" will bring up an editing dialog with all of your presets.
"Aperture→Preferences→Export→Email Photo Export preset" is where you specify which export preset to apply. (You can bring up the editing dialog from here as well.)
Not sure where you got "For Review Only", but one is included as part of the APTS tutorial. Changing this preset is (iirc) one of the lessons.