Your messages and attachments are encrypted using similar methods to the United States Government for its sensitive data. It’s called AES256. In simple terms (you can read more about it on Wikipedia if you’re interested in the technical details) this means that your messages cannot be read by anyone who does not have your password until the time they are made accessible to your recipients. Recipients can only read the messages you sent to them and only when they provide the unique code that they receive in an email from us.
If you delete any of your messages the ‘decryption key’ is also deleted, which means that the message can never be recovered.