Confirmed that mail seems to be piling up on the RCS exchange server for CS accounts since the 27th. Working with the VCC to fix the problem. Email from off campus or regular RCS email is not affected.
4 out of 8 of the RCS dns servers did not have a record for mail.cs.rpi.edu, causing the email delivery problem. The exchange server has been pointed at one of the working servers for now until the problem can be completely fixed.