Mask and Disguise
One of the API calls for the Tadabase Text Utility enables you to Mask values.
Mask Email Address
Pass any string value or just an email address and get a response with the username value of the email masked.
Custom Email Mask
With the custom email mask, you can determine a different character for the username and domain part of the email that needs to be masked.
You can disguise a string using the Disguise API call. Set how many characters should be visible at the end as well as which character to use for disguise and your response text will be disguised.