Hashed email
An email address converted to a one-way cryptographic hash — used for cross-platform identity without storing the plaintext address.
A hashed email is the result of running an email address through a cryptographic hash function (typically SHA-256) to produce a fixed-length string that's deterministic but irreversible. The same email always produces the same hash; the hash can't be reversed to the email.
Hashed emails are widely used for cross-platform identity matching — ad platforms (Meta, Google Ads, LinkedIn) accept hashed email uploads for audience targeting because they can match against their own hashed records without ever exchanging plaintext addresses. The same hash on both sides produces the match.
For data-protection purposes, hashed emails occupy a gray zone. Hashing reduces but doesn't eliminate the personal-data status under GDPR — a hash that can be linked to identifying information is still personal data. Most regulators treat hashed emails as personal data for compliance purposes. Hashing is useful for identity matching, not for privacy laundering.