<p>Don’t worry about it unless you owe them your application fee or something. Even when there’s no balance they send out those emails. Your SID is your directory id or UID# (found at the bottom of your acceptance page at the admissions site, but no decision has been made for you, so I wouldn’t worry about the bill). If I remember correctly, you don’t get to set your testudo password until you formally enter the university. I think you should get a paper copy of the bill if you owe money since you’re a prospective student.</p>