I had a similar thing with glitched images once. We had to retrofit a middleware onto a site that would obfuscate email addresses. It used a regex to spot valid

I had a similar thing with glitched images once. We had to retrofit a middleware onto a site that would obfuscate email addresses. It used a regex to spot valid emails and replaced them with a hash. It also knew what urls and form parameters expected emails and used a lookup table to translate them back. This was sufficient to anonymise usernames without breaking any functionality on the site. Turns out, we forgot to check content type, and valid emails according to the regex we had used were surprisingly common in binaries.