Returns an MD5 hash of a string, as a 32-character string representation of hexadecimal.
MD5-hash a User’s Email Address
Use Case: Pass an anonymized user identifier such as the MD5-hash of their email address in a URL as a query string parameter.
Explanation: Sending the hash of an email address allows you to compare this against your internal record of user hashes and identify the user. (Note that as a security and deliverability best practice, we recommend never directly passing the user’s email address in a URL.) You can use this technique in the Auto-Append Link Parameters section of the Template and Campaign Editors, for example.