I've learned to pretty much ignore that email. Oh sure, I click on the fridge to make sure that there is plenty of food available, then I just ignore it. I think the peeps are "programmed" to send an email every once in a while and there are certain "pre-written" ones that are just chosen randomly. You've just been unlucky in that when your peeps are supposed to send one to you, your game keeps choosing that one.

Although, I did try making two different families vegetarians and I was continually getting that one until I gave in and bought meat and dairy products too. Then I started getting different ones from those two families AS WELL as still getting those occasionally.