If you have received a notification from the Policy Based Encryption service indicating that they have a new mail that should be read in the secure portal, by default the notification displays multiple language choices such as English, Spanish.. etc.
When the user chooses a language, it only arrives in that selected language. Clients can choose to customize the languages based on their companies policies.
Email Security.cloud
In order to customize the default language for the Policy Based Encryption notifications, you will be need to contact the Email cloud support team via a support case.