The Format Preserving Encryption - Email scheme preserves the format of the input text.
For example, Salesforce expects an @ and a dot (.) in an email address, and will reject them as invalid if those attributes are not present. MVISION Cloud encrypts the input email address, then changes the domain to a configurable name, in order to protect the identity of your company. But email attributes are preserved in order to pass validation while protecting the data.
For example, email@example.com would encrypt to Cipher3@myshn.net: which would pass validation at Salesforce, but is indecipherable to unauthorized users.