If you got a confirmation email, then that is all you needed to do. But if there are applicants who did not get the confirmation, then it's best to call the student affairs office or even the financial aid office (at JB) to see the process of your letter. The most important thing is for your letter to get into your file. There it will be reviewed by the deans for admission decisions. The problem is if the letter never makes it into the file, it's most likely because staff responsibilities are too scattered and they unknowingly skipped over the letter. That is why calling and actually talking to someone there will help. But do give them some patience... everyone in there looks extremely overwhelmed. I understand it's frustrating but they are doing the best they can under the circumstances.