I've seen notices from the past where SG has had problems with users building too many addresses off of a username. Seems like I remember it taking down the server (or at least creating huge delays at one point).
I was just reviewing my account and noticed that I've built up 155 addresses off of my primary id and 66 on what I call my 'business' id. Made me wonder - Am I getting too many & will I be the next problem? So how many id's is too many?
I created the business ID to help with this so that I can split out companies I do business with to each have their own and I can control things. For example say McDonalds would get McDonalds.com.x at some SG domain and the king would get burgerKing.com.x, and so on. I figured when I got to 100 on ID (x in this example), I'd create a second business id, and the merriment keeps on going.