You need to create a formula field on the object you are using for the file download. The API name of this formula field will be used to add the custom suffix (e.g., parent record ID) in the downloaded file name.


For example:
If you want to add the Account record ID as a suffix for files downloaded from the Contact object, you can create a formula field on the Contact object that references the related Account’s ID. Then use that formula field’s API name in the Excluded Objects "File Name Suffix" field.

You can follow the same approach for both standard and custom objectsjust create the required formula field and use its API name accordingly.


Steps to create the formula field:

  1. Go to Object Manager in Setup and select the Contact object.
  2. Click on Fields & Relationships > New.
  3. Choose Formula as the field type.
  4. Enter a field label (e.g., “Account ID Suffix”), set the return type to Text, and click Next.
  5. In the formula editor, enter the formula:
    Account.Id
  6. Now, you can use this formula field’s API name (Account_ID_Suffix__c) in the "Excluded Objects" section. Search for the Contact object, and in the "File Name Suffix" column, enter this field’s API name as shown in the image below.
     
  7. Go to the "About Mass File Download" tab and configure the "File Download Configuration" section as shown in the image below.
     
  8. Now, the downloaded file name will include the Contact object file name along with the associated Account record ID whenever you download files from the Contact object. For example, the file name will appear as: FileName-AccountID.