Hash Historical Customer Emails

If you are concerned about sharing historical customer data for data protection purposes, you can provide the list “pre-hashed”. By performing a one-way hash on historical customer email addresses, we can tell if a particular email address is in the list, but we cannot see or discover the original addresses. We also provide a Secure Document Transfer feature for safely sending and receiving sensitive information.

Setting Up the Hashes

You will need a shared secret key from Mention Me. Contact your onboarding manager to obtain the secret before continuing. For each email address:

Lowercase the email

Lowercase the email address.

Append the secret key

Append the secret key provided by Mention Me.

Hash with SHA-256

Hash the combined email address and key using SHA-256.

Verify output format

Ensure the output hash is lowercase.

Testing the Hashes

Hash a known email address (e.g. your own), then use the Test Hashing feature in the platform to compare. Go to Settings & Tools > Test Hashing.

Enter the email address and the hash value you created. The platform confirms if the hash matches. If it does not match, the platform shows the expected value.

Hash test result showing match confirmation

Code Examples

Pseudo-Code

HashedEmail = LowerCase(SHA256Hash(Concatenate(LowerCase([EMAIL]), [KEY])))

MySQL

SELECT SHA2(CONCAT(LOWER(u.email), SECRET), 256)
FROM user u;

T-SQL (MS SQL Server)

SELECT LOWER(
  CONVERT(
    VARCHAR(200),
    HASHBYTES(
      'SHA2_256',
      CONCAT(
        LOWER(CAST(u.email AS VARCHAR(256))),
        SECRET
      )
    ),
    2)
)
FROM user u;

JavaScript

var crypto = require("crypto");

var input = email.toLowerCase() + secret;
var output = crypto.createHash("sha256").update(input).digest("hex");
console.log(output);

Last modified on July 10, 2026

Understanding Hashed Data How to Upload Historical Orders

⌘I

Getting Started

Onboarding

Referral

Influencer

A/B Testing

Reporting

Integrations

Security & Data

Platform Reference

Hash Historical Customer Emails

Setting Up the Hashes

Testing the Hashes

Code Examples

Pseudo-Code

MySQL

T-SQL (MS SQL Server)

JavaScript

​Setting Up the Hashes

​Testing the Hashes

​Code Examples

​Pseudo-Code

​MySQL

​T-SQL (MS SQL Server)

​JavaScript

Setting Up the Hashes

Testing the Hashes

Code Examples

Pseudo-Code

MySQL

T-SQL (MS SQL Server)

JavaScript