AI delivered a cake yesterday w/ SMBC (used pasteurized egg whites and additionally heated it) and she called me today saying that some of it started melting and that she left it on her counter all night. Should I advise her not to eat it since it's been exposed to a "temperature danger zone" for a good 15 hours?!

yes probably -- she spoiled her cake --should have been kept in a cool to cold place -- was it the exhaust of a fridge or something? had to be pretty warm to melt it -- dang i hate that happened!

i don't think you should bear any responsibility with what you have said so far but did you advise her to fridge it? 

i said 'probably' because think if royal icing melted it would not spoil anything necessarily but there's no milk fats in royal -- really kind of a borderline determination but still i would not eat it and it's safe to err on the side of caution --

i'm sure someone could pipe up and say i kept my cream cheese (yours doesn't have cc i'm just saying) out for 7 days before i made the icing and then it melted and we used it the next month as syrup for our ice cream and "nobody died" and it was really cool how it bubbled up ;)

so i'd advise her of that but be careful to not take responsibility -- had to be in the nineties or by some kind of warm moving air which is not your problem --

AHuh, I totally didn't think about that- it being in the nineties. She never sent a pic so I'm not sure how much melting went on. I advised her in a very long email chain that it will stay good in the refrigerator if she has it for a long period of time. I'm currently in the middle of serve safe classes and everything is starting to scare the bojangles out of me! Thanks for the response k8 Memphis!

I recommend putting labels on your boxed desserts that say keep refrigerated or store at room temperature.

That;s what I do.  Write in magic marker on the box PLEASE KEEP REFRIGERATED.  

Nice! I definitely will do that!