Mask all but last 4 of merge field
I'm using a transactional survey, comprised mostly of merge fields, and business rules to send receipt for some of our forms. In some of the forms we request sensitive information, e.g. account numbers. I see there's a way for merge fields to only show the first x amount of characters, but I'd prefer to only show the last 4 characters. I'm basically looking for similar functionality as Incident Thread Masking to take place in my message templates and mailings, specifically targeting the merge fields. Anyone know if this is possible?