You should be getting a monthly email receipt from PayPal. It is possible that the receipts are going into your junk/spam folder.
The best suggestions would be to:
a) check your junk/spam folder locally
b) check your online junk/spam folder (many mail services screen and trap spam on the server, and this e-mail can be viewed through your online webmail service).
The e-mail receipt will come from firstname.lastname@example.org
If the address NEEDS to be whitelisted, it's likely that it's in one of those two places. If you have your mail server set to delete flagged mail immediately, you may never see the email. In this case whitelisting the address will help.
If for some reason it does not make it to your host server, there is very little that we can do to troubleshoot or correct the issue.
If this is the case - please e-mail email@example.com and we can provide you with a copy of the receipt.
Please include the following:
-your University user name
-the email address that you signed up with
-the date of the transaction.