I also received this letter yesterday and had no portal update saying my file was closed. I received the following email the night prior (Friday):
BOTTOM LINE UP FRONT: Please check your USMA Candidate Portal
The USMA file completion deadline recently passed and as a routine action, the USMA Admissions office closed a relatively large number of files due to insufficient progress. Owing to some technological issues, a few candidates files were closed for a brief period, which in turn caused a postal letter to be mailed out. If you received a hardcopy letter in the mail informing you that your USMA application file was closed, there is a very small chance that this letter was sent to you in error.
If you believe you received this postal mailing, you are encouraged to check your candidate portal to determine your file status. Whatever you see on the portal is your true USMA application status. Whether the candidate portal says your file is open or closed, that can be trusted as it is your correct file status.
Thank you and we apologize for any confusion. Go Army!
Respectfully,
Mr. Damien J. King
Data Manager, Directorate of Admissions
United States Military Academy
West Point, NY 10996
CHECK YOUR PORTAL! Your portal will have the most up-to-date information, so if it doesn't say your file is closed this was most likely a mistake. Personally, my portal was not closed when I looked.