How to enable MD5 suppression
Head to the campaigns tab and select "add new campaign"
Select the type as "Suppression" and the "Encryption type" as MD5
Set up any additional settings and then select "Save and go to fields"
Here you can see the fields automatically hashed in MD5, and any additional fields you wish to encrypt.
Once you have saved these fields you can head back to your main campaign and "update settings".
Scroll down to "Deduplication" and in the "Check against campaigns" drop down list, select the suppression campaign in MD5 you previously created.
Don't forget to save any changes you have made.
Once you post in leads into this suppression campaign, you'll see them as a hash value under the lead info: