You can use the S120 tag to pull in the custom_string for the Custom Data Element. To build out the S120 tag, you will need to follow these steps:
  1. Navigate to the donation form in question
  2. Edit the donation form
  3. Go to step 5. Configure Autoresponders
  4. Go to step b. Edit HTML Content
  5. In the Plain Text Editor, place your cursor in an empty space
  6. From the drop-down menus at the top of the editor, choose Personalization - Other
  7. In the pop-up window, choose Donation Custom Fields from the Field Group selections
  8. Choose the custom data element you want to use from the Field selections
  9. Click Insert
  10. In the Plain Text Editor, you should see the information that was just inserted, and you will find the populated S120 tag ( it'll look similar to this: [[S120:dc:custom:custom_string1]] )
  11. Copy the S120 tag
  12. click cancel
You can now copy and paste the S120 tag wherever you need to use inside the autoresponders.