Originally Posted by Largepotato

Is there a cap on how much stuff can be left stored in the gift box?

Once it's over 100 items, it gets difficult to use. You can't see the oldest items, only the newest 100, so you run some risk of having things expire if you stay over 100 for too long. For short periods of time, I haven't hit a real limit but I haven't tried to push it either.