Hashed Suppression List Support (MD5 & SHA256)

Hashed Suppression List Support (MD5 & SHA256)

Hashed Suppression List Support is an enhancement to our suppression system designed to provide greater security and flexibility. While our system previously required plain-text email addresses for suppression, this update allows you to upload suppression lists using hashed values. This is particularly valuable for enterprise customers who need to exchange data securely without exposing raw email addresses.

How it works

To address the limitations of plain-text requirements, we have introduced support for the two most common hashed formats. Customers can now upload suppression files containing either:
  1. A 32-character MD5 hash
  2. A 64-character SHA256 hash

The Matching Process 

During contact ingestion, the system automatically normalizes each email address — converting it to lowercase and trimming any spaces — before generating and storing both MD5 and SHA256 hashes. This ensures consistency and prevents mismatches due to formatting differences.

When a hashed suppression file is uploaded, the system matches the uploaded hash values directly against the precomputed hashes stored for your contacts. If a match is found, the corresponding user is suppressed automatically.

Key Benefits

From a business perspective, shifting to hashed suppression enables:
  1. Secure exchanges: Share suppression lists without exposing raw email data.
  2. Industry alignment: Adheres to industry-standard hashed data practices.
  3. Improved compliance: Strengthens your overall compliance posture.
  4. Reduced operational overhead: Streamlines the process for enterprise customers who already utilize hashed data.



Processing and Confirmation

Once you upload your file, the suppression status is reflected in your account. You will receive a clear confirmation once the processing is complete, ensuring that your suppression lists are accurate and reliable.



This update enhances our suppression infrastructure by improving security, increasing flexibility, and ensuring it meets enterprise-level standards and scalability requirements.