Today I got an email with a subject "We're closing your accounts", and the body below. Note that I have no credit card with them. Only a checking account with over $2,000 and a savings account with over $30,000. I don't use the account frequently, but transfer in/out about 5-10 times a year. I called in and they had nothing to add about why it was closed. Their security department was kind enough to confirm that no fraudulent activity occurred, but they could not add to the explanation of why it was closed.
Here is the email I received (I've removed my name and placed instead:
Customer Number: XXXXXXXXXX
When you opened your accounts, you agreed to the Account Disclosures reserving our right to close your accounts at any time, for any reason. We closed your 360 Savings and your 360 Checking, including your Overdraft Line of Credit and Debit MasterCard®, on 06/04/2014.
We sent the funds - plus any interest earned - to your linked external checking account and they'll arrive in 2-3 business days. If you don't have a link or your link's closed, a check will arrive by mail within 10-12 business days at your address on file.
Going forward, no additional activity can take place and no new accounts can be opened.
Capital One 360