New Boxcryptor users must verify their account in order to ensure that only valid email-addresses by real humans are used. If an account has not been verified within 7 days after creation, it may not be used anymore. In the past, account verification has only been checked when signing in on a new device. Existing devices could be used even past the 7 days grace period and account verification could be circumvented.
We have deployed a change yesterday which now also enforces account verification for existing devices and automatically unlinks a device if the account is older than 7 days but has not been verified yet. I'm sorry for the inconveniences this change caused in your organization. We should have done a better job either communicating this change in advance or grandfathering older accounts with existing devices.